U.S. patent number 7,762,964 [Application Number 10/498,382] was granted by the patent office on 2010-07-27 for method and apparatus for improving safety during exposure to a monochromatic light source.
This patent grant is currently assigned to Candela Corporation. Invention is credited to Michael Slatkine.
United States Patent |
7,762,964 |
Slatkine |
July 27, 2010 |
Method and apparatus for improving safety during exposure to a
monochromatic light source
Abstract
A method and apparatus are disclosed for enhancing the
absorption of light in targeted skin structures. A vacuum chamber
having a clear transmitting element transparent to intense pulsed
light on its proximate end and an aperture on its distal end is
placed on a skin target. After applying a vacuum to the vacuum
chamber and modulating the applied vacuum, the concentration of
blood and/or blood vessels is increased within a predetermined
depth below the skin surface of the skin target. Optical energy
associated with intense pulsed light directed in a direction
substantially normal to a skin surface adjoining the skin target is
absorbed within the predetermined depth. The apparatus is suitable
for treating vascular lesions with a reduced treatment energy
density level than that of the prior art and for evacuating
condensed vapors produced during the cooling of skin prior to
firing an intense pulsed light with a controlled delay.
Inventors: |
Slatkine; Michael (Herzlia,
IL) |
Assignee: |
Candela Corporation (Wayland,
MA)
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Family
ID: |
41395078 |
Appl.
No.: |
10/498,382 |
Filed: |
August 2, 2002 |
PCT
Filed: |
August 02, 2002 |
PCT No.: |
PCT/IL02/00635 |
371(c)(1),(2),(4) Date: |
October 18, 2004 |
PCT
Pub. No.: |
WO03/049633 |
PCT
Pub. Date: |
June 19, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050234527 A1 |
Oct 20, 2005 |
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US 20090299440 A9 |
Dec 3, 2009 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/IL02/00635 |
Aug 2, 2002 |
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10614672 |
Jul 7, 2003 |
7184614 |
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Foreign Application Priority Data
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Dec 10, 2001 [IL] |
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147009 |
Jun 6, 2002 [IL] |
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150094 |
Feb 22, 2004 [IL] |
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160510 |
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Current U.S.
Class: |
601/7;
601/15 |
Current CPC
Class: |
A61B
18/203 (20130101); A61B 90/04 (20160201); A61B
2018/00458 (20130101); A61B 2018/2261 (20130101); A61B
2018/1807 (20130101); A61B 2018/00023 (20130101); A61B
2018/00452 (20130101); A61B 2090/049 (20160201); A61B
2018/00476 (20130101); A61N 5/0616 (20130101); A61B
2017/00172 (20130101) |
Current International
Class: |
A61H
7/00 (20060101) |
Field of
Search: |
;601/7,10,15,DIG.1,DIG.4,DIG.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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933096 |
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2001-212231 |
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JP |
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JP |
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WO 99/27863 |
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WO |
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WO 99/27863 |
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WO |
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WO 99/46005 |
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WO00/60711 |
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WO 00/72771 |
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WO 00/72771 |
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2003/103523 |
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WO |
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WO 2004/004803 |
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Jan 2004 |
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WO |
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Other References
"The Physiology Coloring Book", W. Kapit et al., Harper Collins
Publishers, 1987, pp. 88-89. cited by other .
International Search Report for PCT/IL02/00635 (5 pages). cited by
other .
International Preliminary Examination Report for PCT/IL02/00635 (7
pages). cited by other .
"Effects of Tissue Optical Clearing, . . ,Lasers Light within
Tissue (G. Vergas & A.J. Welch, Laser in Surgery and Medicine",
Supp. 13, 2001, p. 26). cited by other .
PCT International Search Report for corresponding PCT application
(PCT/IL02/00635) (6 pages). cited by other .
PCT International Search Report for PCT application
(PCT/IL03/00277) (3 pages). cited by other.
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Primary Examiner: Brown; Michael A.
Attorney, Agent or Firm: Proskauer Rose LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of international
application no. PCT/IL02/00635, filed on Aug. 2, 2002, which claims
the benefit of and priority to Israeli patent application no.
147009, filed on Dec. 10, 2001, and Israeli patent application no.
150094, filed on Jun. 6, 2002. This application also claims the
benefit of and priority to Israeli patent application no. 160510,
filed on Feb. 22, 2004. This application is also a
continuation-in-part of U.S. application Ser. No. 10/614,672, filed
Jul. 7, 2003, now U.S. Pat. No. 7,184,614.
Claims
The invention claimed is:
1. An apparatus for enhancing the absorption of light in targeted
skin structures, comprising: an intense pulsed light source; a
U-shaped evacuation chamber positionable on a skin target; a
handpiece for directing intense pulsed light to the skin target
which is connected to, or integral with, the evacuation chamber; a
clear transmitting element mounted in the distal end of the
U-shaped evacuation chamber, the transmitting element being
transparent to intense pulsed light directed to the skin target and
suitable for transmitting the intense pulsed light in a direction
substantially normal to a skin surface adjoining the skin target; a
rim for sealing the peripheral contact area between the skin
surface adjoining the skin target and the wall of the handpiece;
and means for applying a vacuum to the evacuation chamber including
a first conduit and a second conduit in communication with the
U-shaped evacuation chamber, the second conduit including a distal
opening that can be occluded during vacuum application, the level
of the applied vacuum suitable for drawing the skin target to the
evacuation chamber and for increasing the concentration of blood
and/or blood vessels within a predetermined depth below the skin
surface of the skin target, optical energy associated with the
directed intense pulsed light being absorbed within the
predetermined depth.
2. The apparatus according to claim 1, wherein the vacuum applying
means comprises a vacuum pump and at least one control valve.
3. The apparatus according to claim 1, further comprising control
means for controlling operation of the vacuum pump, the at least
one control valve, and the intense pulsed light source.
4. The apparatus according to claim 3, wherein the control means is
suitable for firing the intense pulsed light source after a
predetermined delay following operation of the vacuum pump.
5. The apparatus according to claim 3, wherein the control means is
suitable for firing the intense pulsed light source after a
predetermined delay following opening of the at least one control
valve.
6. The apparatus according to claim 5, wherein the control means is
suitable for increasing the pressure in the evacuation chamber to
atmospheric pressure following deactivation of the intense pulsed
light source, to allow the effortless repositioning of the
evacuation chamber to a second skin target.
7. The apparatus according to claim 3, further comprising a pulsed
radio frequency (RF) source for directing suitable electromagnetic
waves to the skin target.
8. The apparatus according to claim 7, wherein the frequency of the
electromagnetic waves ranges from 0.2 to 10 MHz.
9. The apparatus according to claim 7, wherein the RF source is a
bipolar RF generator which generates alternating voltage applied to
the skin surface via wires and electrodes.
10. The apparatus according to claim 7, wherein the control means
is suitable for transmitting a first command pulse to the at least
one control valve and a second command pulse to both the intense
pulsed light source and RF source.
11. The apparatus according to claim 3, further comprising an
erythema sensor, said sensor suitable for measuring the degree of
skin redness induced by the vacuum applying means.
12. The apparatus according to claim 11, wherein the control means
is suitable for controlling, prior to firing the light source, the
energy density of the light emitted from the light source, in
response to the output of the erythema sensor.
13. The apparatus according to claim 1, wherein the intense pulsed
light source is selected from a group comprising a Dye laser,
Nd:YAG laser, Diode laser, Alexandrite laser, Ruby laser, Nd:YAG
frequency doubled laser, Nd:Glass laser and a non-coherent intense
pulse light source.
14. The apparatus according to claim 1, wherein the light emitted
from the light source has any wavelength band between 400 nm and
1800 nm.
15. An apparatus for enhancing the absorption of light in targeted
skin structures, comprising: an intense pulsed light source; a
handpiece for directing light from the intense pulsed light source
to the targeted skin structures, the intense pulsed light source
connected to, or integral with, the handpiece, the handpiece
further comprising: an evacuation chamber defined by a wall of the
handpiece, the evacuation chamber positionable on a region of skin
including the targeted skin structures; a transmitting element
mounted in the distal end of the evacuation chamber, the
transmitting element being substantially transparent to the light
directed to the targeted skin structures, and suitable for
transmitting the light in a direction substantially normal to a
skin surface of the region of skin including the targeted skin
structures; and a rim on an end of the wall for sealing a
peripheral contact area between the skin surface and the wall of
the handpiece; a vacuum system for applying vacuum to draw the
region of skin including the targeted skin structures into the
evacuation chamber; and a first conduit and a second conduit
defined in the evacuation chamber, the first conduit communicating
vacuum to the evacuation chamber, the second conduit including a
distal opening that can be occluded during vacuum application,
optical energy associated with the light being absorbed within a
predetermined depth below the skin surface of the skin target.
16. The apparatus of claim 15 wherein the vacuum system is
configured to apply a level of vacuum suitable for increasing the
concentration of blood and/or blood vessels within the
predetermined depth
17. The apparatus of claim 15 wherein the vacuum system comprises a
vacuum pump and at least one control valve associated with the
first conduit.
18. The apparatus of claim 17 further comprising control means for
controlling operation of the vacuum pump, the at least one control
valve, and the intense pulsed light source.
19. The apparatus of claim 18 wherein the control means is suitable
for firing the intense pulsed light source after a predetermined
delay following operation of the vacuum pump.
20. The apparatus of claim 18 wherein the control means is suitable
for firing the intense pulsed light source after a predetermined
delay following opening of the at least one control valve.
21. The apparatus of claim 18 wherein the control means is suitable
for increasing the pressure in the evacuation chamber to
atmospheric pressure following deactivation of the intense pulsed
light source, to allow the effortless repositioning of the
evacuation chamber to a second skin target region.
22. The apparatus of claim 15 wherein the intense pulsed light
source is selected from the group comprising a dye laser, a Nd:YAG
laser, a diode laser, an alexandrite laser, a ruby laser, a Nd:YAG
frequency doubled laser, a Nd:Glass laser and a non-coherent
intense pulse light source.
23. The apparatus of claim 15 wherein the light emitted from the
intense pulsed light source has one or more wavelengths from about
400 nm to about 1800 nm.
24. The apparatus of claim 15 wherein the intense pulsed light
source is a diode laser.
25. The apparatus of claim 15 wherein the intense pulsed light
source is a non-coherent intense pulse light source.
26. The apparatus of claim 15 wherein the second conduit includes a
valve for occluding the distal opening.
27. The apparatus of claim 26 further comprising a controller
adapted to operate the vacuum system, the valve for occluding the
distal opening, and the intense pulsed light source.
Description
FIELD OF THE INVENTION
The present invention is related to the field of laser-based light
sources. More specifically, the invention is related to the
utilization of light sources for the non-invasive treatment of skin
disorders, whereby light is selectively absorbed by blood vessels,
for the treatment or destruction of blood vessels.
BACKGROUND OF THE INVENTION
Prior art very high intensity, short duration pulsed light systems
which operate in the visible part of the spectrum, such as
flashlamps or intense pulsed lasers are currently used in aesthetic
treatments by one of two known ways: a) Applying the light to the
skin without applying any pressure on the treatment zone, so as not
to interfere with the natural absorption properties of skin; and b)
Applying pressure onto the skin by means of the exit window of the
treatment device in contact with the skin, thereby expelling blood
from the light path within the skin and enabling better
transmission of the light to a skin target.
The major applications of intense pulsed light or intense pulsed
laser systems are hair removal, coagulation of blood vessels for
e.g. port wine stains, telangectasia, spider veins and leg veins,
multiple heating of blood vessels for e.g. rosacea, treatment of
pigmented skin such as erasure of black stains and sun stains or
tattoo removal; and removal of fine wrinkles by heating the tissue
around the wrinkles, normally referred to as photorejuvenation.
U.S. Pat. Nos. 5,226,907, 5,059,192, 5,879,346, 5,066,293,
4,976,709, 6,120,497, 6,120,497, 5,626,631, 5,344,418, 5,885,773,
5,964,749, 6,214,034 and 6,273,884 describe various laser and
non-coherent intense pulsed light systems. These prior art light
systems are not intended to increase the natural absorption of the
skin.
U.S. Pat. Nos. 5,595,568 and 5,735,844 describe a system for hair
removal whereby pressure is applied to the skin by a transparent
contact device in contact therewith, in order to expel blood
present in blood vessels from a treatment zone. In this approach
blood absorption decreases in order to increase subcutaneous light
penetration.
Applying a vacuum to the skin is a known prior art procedure, e.g.
for the treatment of cellulites, which complements massaging the
skin. Such a procedure produces a flow of lymphatic fluids so that
toxic substances may be released from the tissue. As the vacuum is
applied, a skin fold is formed. The skin fold is raised above the
surrounding skin surface, and the movement of a handheld suction
device across the raised skin performs the massage. The suction
device is moved in a specific direction relative to the lymphatic
vessels, to allow lymphatic fluids to flow in their natural flow
direction. The lymphatic valve in each lymphatic vessel prevents
the flow of lymphatic fluid in the opposite direction, if the
suction device were moved incorrectly. Liquids generally accumulate
if movement is not imparted to the raised skin. The massage, which
is generally carried out by means of motorized or hand driven
wheels or balls, draws lymphatic fluids from cellulite in the
adipose subcutaneous region and other deep skin areas, the depth
being approximately 5-10 mm below the dermis.
U.S. Pat. No. 5,961,475 discloses a massaging device with which
negative pressure is applied to the skin together during massaging.
A similar massaging device which incorporates a radio frequency
(RF) source for the improvement of lymphatic flow by slightly
heating the adipose tissue is described in U.S. Pat. No. 6,662,054.
Some massaging systems, such as those produced by Deka and
Cynosure, add a low power, continuous working (CW) light source of
approximately 0.1-2 W/cm.sup.2, in order to provide deep heating of
the adipose tissue by approximately 1.3.degree. C. degrees and to
enhance lymphatic circulation. The light sources associated with
vacuum lymphatic massage devices are incapable of inducing blood
vessel coagulation due to their low power. Also, prior art vacuum
lymphatic massage devices are adapted to induce skin protrusion or
to produce a skin fold by applying a vacuum.
Selective treatment of blood vessels by absorption of intense
pulsed laser radiation is possible with Dye lasers operating at 585
nm, as well as with other types of lasers. Photorejuvenation has
also been performed with Diode lasers in the near infrared spectral
band of 800-980 nm and with Nd:YAG lasers having a frequency of
approximately 1064 nm with limited success. The light emitted by
such lasers is not well absorbed by tiny blood vessels or by the
adjoining liquid. Broad band non-coherent intense pulsed light
systems are also utilized for photorejuvenation with some success,
although requiring more than 10 repeated treatments. The heat which
is absorbed by the blood vessels, as a result of the light emitted
by the intense short pulse devices, is transferred to adjacent
collagen bundles.
The absorption of pulsed Diode and Nd:YAG laser beams by blood
vessels is lower than the absorption of pulsed Dye laser beam. In
order to compensate for limited photorejuvenation with red and
infrared intense pulsed light and laser systems, a very high energy
density as high as 30-60 J/cm.sup.2 needs to be generated. At such
an energy density, the melanin-rich epidermis, particularly in dark
skin, is damaged if not chilled. A method to reduce the energy
density of intense pulsed lasers or non-coherent intense pulsed
light sources which operate in the visible or the near infrared
regions of the spectrum will therefore beneficial.
Pulsed dye lasers operating in the yellow spectral band of
approximately 585-600 nm, which is much better absorbed by blood
vessels, are also utilized for the smoothing of fine wrinkles. The
energy density of light emitted by Dye lasers, which is
approximately 3-5 J/cm.sup.2, is much lower than that of light
emitted by other lasers. However, the pulse durations of light
emitted by Dye lasers are very short, close to 1 microsecond, and
therefore risk the epidermis in darker skin. Treatments of wrinkles
with Dye lasers are slow, due to the low concentration of absorbing
blood vessels, as manifested by the yellow or white color of
treated skin, rather than red or pink characteristic of skin having
a high concentration of blood vessels. Due to the low energy
density of light emitted by Dye lasers, as many as 10 treatments
may be necessary. A method to reduce the energy density of light
generated by Dye lasers, or to reduce the number of required
treatments at currently used energy density levels, for the
treatment of fine wrinkles, would be beneficial.
Pulsed Dye lasers operating at 585 nm are also utilized for the
treatment of vascular lesions such as port wine stains or
telangectasia or for the treatment of spider veins. The energy
density of the emitted light is approximately 10-15 J/cm.sup.2, and
is liable to cause a burn while creating the necessary purpura. A
method to reduce the energy density of light emitted by Dye lasers
for the treatment of vascular lesions would be highly
beneficial.
Hair removal has been achieved by inducing the absorption of
infrared light, which is not well absorbed by melanin present in
hair strands, impinging on blood vessels. More specifically,
absorption of infrared light by blood vessels at the distal end of
hair follicles contributes to the process of hair removal. High
intensity pulsed Nd:YAG lasers, such as those produced by Altus,
Deka, and Iridex, which emit light having an energy density of more
than 50 J/cm.sup.2, are used for hair removal. The light
penetration is deep, and is often greater than 6 millimeters. Some
intense pulsed light or pulsed laser systems, such as that produced
by Syneron, used for hair removal or photorejuvenation also employ
an RF source for further absorption of energy within the skin.
The evacuation of smoke or vapor, which is produced following the
impingement of monochromatic light on a skin target, from the gap
between the distal end window of a laser system and the skin
target, is carried out in conjunction with prior art ablative laser
systems such as CO.sub.2, Erbium or Excimer laser systems. The
produced smoke or vapor is purged by the introduction of air at
greater than atmospheric pressure. Coagulative lasers such as
pulsed dye lasers or pulsed Nd:YAG lasers, which treat lesions
under the skin surface, are not provided with an evacuation
chamber.
Some prior art intense pulsed laser systems, which operate in the
visible and near infrared region of the spectrum and treat lesions
under the skin surface, e.g. vascular lesions, with pulsed dye
laser systems or pulsed Nd:YAG lasers, employ a skin chilling
system. Humidity generally condenses on the distal window, due to
the use of a skin chilling system. It would be advantageous to
evacuate the condensed vapors from the distal window of the laser
system prior to the next firing of the laser.
It is an object of the present invention to provide a method and
apparatus for the treatment of subcutaneous lesions, such as
vascular lesions, by a high intensity pulsed laser system operating
at wavelengths shorter than 1800 nm without causing a burn to the
epidermis.
It is an object of the present invention to provide a method and
apparatus for controlling the depth of subcutaneous light
absorption.
It is an object of the present invention to provide a method and
apparatus for increasing the absorption of light which impinges a
skin target by increasing the concentration of blood vessels
thereat.
It is an additional object of the present invention to provide a
method and apparatus by which the energy density level of intense
pulsed light that is suitable for hair removal, fine wrinkle
removal, including removal of wrinkles around the eyes and in the
vicinity of the hands or the neck, and the treatment of port wine
stain or rosacea may be reduced relative to that of the prior
art.
It is an additional object of the present invention to provide a
method and apparatus by which the number of required treatments for
hair removal, fine wrinkle removal, including removal of wrinkles
around the eyes and in the vicinity of the hands or the neck, and
the treatment of port wine stain or rosacea at currently used
energy density levels may be reduced relative to that of the prior
art.
It is yet an additional object of the present invention to provide
a method and apparatus for repeated evacuation, prior to the firing
of a subsequent laser pulse, of vapors which condensed on the
distal window due to the chilling of laser treated skin.
Other objects and advantages of the invention will become apparent
as the description proceeds.
SUMMARY OF THE INVENTION
The present invention comprises a method for controlling the depth
of light absorption by blood vessels under a skin surface
comprising placing a vacuum chamber which is transparent to intense
pulsed light on a skin target; applying a vacuum to said vacuum
chamber, whereby said skin target is drawn to said vacuum chamber
and the concentration of blood and/or blood vessels within said
skin target is increased; modulating the applied vacuum so that the
concentration of blood and/or blood vessels is increased within a
predetermined depth below the skin surface; and directing intense
pulsed light to said skin target, optical energy associated with
the directed intense pulsed light being absorbed within said
predetermined depth.
The depth under the skin surface at which optical energy is
absorbed may be selected in order to thermally injure or treat
predetermined skin structures located at said depth. As referred to
herein, a "skin structure" is defined as any damaged or healthy
functional volume of material located under the epidermis, such as
blood vessels, collagen bundles, hair shafts, hair follicles,
sebaceous glands, sweat glands, adipose tissue. Depending on the
blood concentration within the skin target, the intense pulsed
light may propage through the skin surface and upper skin layers
without being absorbed thereat and then being absorbed at a skin
layer corresponding to that of a predetermined skin structure. As
referred to herein, the term "light" means both monochromatic and
non-coherent light. The terms "light absorption" and "optical
energy absorption" refer to the same physical process and are
therefore interchangeable.
In contrast with a prior art vacuum-assisted method of laser or
intense pulsed light treatment wherein a skin fold is produced
following application of the vacuum, vacuum-assisted drawn skin in
accordance with the method of the present invention is not
distorted, but rather is slightly and substantially uniformly drawn
to the vacuum chamber, protruding approximately 1 mm from the
adjoining skin surface. The maximum protrusion of the drawn skin
from the adjoining skin surface is limited by a clear transmitting
element defining the proximate end of the vacuum chamber. The clear
transmitting element is separated from the adjoining skin surface
by a gap of preferably 2 mm, and ranging from 0.5-40 mm.
As referred to herein, "vacuum modulation" means adjustment of the
vacuum level within, or of the frequency by which vacuum is applied
to, the vacuum chamber. By properly modulating the vacuum, the
blood flow rate, in a direction towards the vacuum chamber, within
blood vessels at a predetermined depth below the skin surface can
be controlled. As the concentration of blood and/or blood vessels
is increased within the skin target, the number of light absorbing
chromophores is correspondingly increased at the predetermined
depth. The value of optical energy absorbence at the predetermined
depth, which directly influences the efficacy of the treatment for
skin disorders, is therefore increased.
Preferably a) The wavelength of the intense pulsed light ranges
from 400 to 1800 nm. b) The pulse duration of the intense pulsed
light ranges from 10 nanoseconds to 900 msec. c) The energy density
of the intense pulsed light ranges from 2 to 150 J/cm.sup.2. d) The
level of the applied vacuum within the vacuum chamber ranges from 0
to 1 atmosphere. e) The frequency of vacuum modulation ranges from
0.2 to 100 Hz. f) The intense pulsed light is fired after a
predetermined delay following application of the vacuum. g) The
predetermined delay ranges from 10 msec to 1 second. h) The
duration of vacuum application to the vacuum chamber is less than 2
seconds. i) Vacuum modulation is electronically controlled.
Due to implementation of the method of the present invention, the
treatment energy density level for various types of treatment is
significantly reduced, on the average of 50% with respect with that
associated with prior art devices. The treatment energy density
level is defined herein as the minimum energy density level which
creates a desired change in the skin structure, such as coagulation
of a blood vessel, denaturation of a collagen bundle, destruction
of cells in a gland, destruction of cells in a hair follicle, or
any other desired effects. The following is the treatment energy
density level for various types of treatment performed with use of
the present invention: a) treatment of vascular lesions, port wine
stains, telangectasia, rosacea, and spider veins with light emitted
from a dye laser unit and having a wavelength of 585 nm: 5.12
J/cm.sup.2; b) treatment of vascular lesions, port wine stains,
telangectasia, rosacea, and spider veins with light emitted from a
diode laser unit and having a wavelength of 940 nm: 10-30
J/cm.sup.2; c) treatment of vascular lesions with light emitted
from an intense pulsed non-coherent light unit and having a
wavelength of 570-900 nm: 5-20 J/cm.sup.2; d) photorejuvination
with light emitted from a dye laser unit and having a wavelength of
585 nm: 1-4 J/cm.sup.2; e) photorejuvination with light emitted
from an intense pulsed non-coherent light unit and having a
wavelength of 570.900 nm: 5.20 J/cm.sup.2; f) photorejuvination
with a combined effect of light emitted from an intense pulsed
non-coherent light unit and having a wavelength of 570-900 nm and
of a RF source: 10 J/cm.sup.2 for both the intense pulsed
non-coherent light unit and RF source; and g) hair removal with
light emitted from a Nd:YAG laser unit and having a wavelength of
1604 nm: 25.35 J/cm.sup.2.
The present invention is also directed to an apparatus for
enhancing the absorption of light in targeted skin structures,
comprising: a) a vacuum chamber placed on a skin target which is
formed with an aperture on the distal end thereof and provided with
a clear transmitting element on the proximate end thereof, said
transmitted element being transparent to intense pulsed light
directed to said skin target and suitable for transmitting the
intense pulsed light in a direction substantially normal to a skin
surface adjoining said skin target; b) means for applying a vacuum
to said vacuum chamber, the level of the applied vacuum suitable
for drawing said skin target to said vacuum chamber via said
aperture; and c) means for modulating the applied vacuum in such a
way that the concentration of blood and/or blood vessels is
increased within a predetermined depth below the skin surface of
said skin target, optical energy associated with the directed
intense pulsed light being absorbed within said predetermined
depth.
As referred to herein, "distal" is defined as a direction towards
the exit of the light source and "proximate" is defined as a
direction opposite from a distal direction.
The ratio of the maximum length to maximum width of the aperture
formed on the distal end of the vacuum chamber ranges from
approximately 1 to 4.
In one embodiment of the invention, the vacuum chamber is connected
to, or integrally formed with, a proximately disposed handpiece
through which intense pulsed light propagates towards the skin
target.
The intense pulsed light is suitable for hair removal,
photorejuvenation, treatment of vascular lesions, treatment of
sebaceous or sweat glands, treatment of warts, or treatment of
pigmented lesions.
The present invention is also directed to an apparatus for
enhancing the absorption of light in targeted skin structures,
comprising: a) an intense pulsed light source; b) a U-shaped
evacuation chamber positionable on a skin target; c) a handpiece
for directing intense pulsed light to a skin target which is
connected to, or integral with, said evacuation chamber; d) a clear
transmitting element mounted in the distal end of said handpiece,
said transmitted element being transparent to intense pulsed light
directed to said skin target and suitable for transmitting the
intense pulsed light in a direction substantially normal to a skin
surface adjoining said skin target; e) a rim for sealing the
peripheral contact area between the skin surface adjoining said
skin target and the wall of the handpiece; and f) means for
applying a vacuum to said evacuation chamber, the level of the
applied vacuum suitable for drawing said skin target to said
evacuation chamber and for increasing the concentration of blood
and/or blood vessels within a predetermined depth below the skin
surface of said skin target, optical energy associated with the
directed intense pulsed light being absorbed within said
predetermined depth.
The terms "evacuation chamber" and "vacuum chamber" as referred to
herein are interchangeable.
The vacuum applying means preferably comprises a vacuum pump and at
least one control valve.
The apparatus preferably further comprises control means for
controlling operation of the vacuum pump, the at least one control
valve, and the intense pulsed light source. The control means is
suitable for firing the intense pulsed light source after a
predetermined delay following operation of the vacuum pump.
Alternatively, the control means is suitable for firing the intense
pulsed light source after a predetermined delay following opening
of the at least one control valve.
The control means is also suitable for increasing the pressure in
the evacuation chamber to atmospheric pressure following
deactivation of the intense pulsed light source, to allow for
effortless repositioning of the evacuation chamber to a second skin
target.
The intense pulsed light source is selected from the group of Dye
laser, Nd:YAG laser, Diode laser, Alexandrite laser, Ruby laser,
Nd:YAG frequency doubled laser, Nd:Glass laser and a non-coherent
intense pulse light source. The light emitted from the light source
has any wavelength band between 400 nm and 1800 nm.
In one aspect, the apparatus further comprises a pulsed radio
frequency (RF) source for directing suitable electromagnetic waves
to the skin target. The frequency of the electromagnetic waves
ranges from 0.2-10 MHz. The RF source is preferably a bipolar RF
generator which generates alternating voltage applied to the skin
surface via wires and electrodes. The control means is suitable for
transmitting a first command pulse to the at least one control
valve and a second command pulse to both the intense pulsed light
source and RF source.
In one aspect, the apparatus further comprises an erythema sensor,
said sensor suitable for measuring the degree of skin redness
induced by the vacuum applying means. The control means is suitable
for controlling, prior to firing the light source, the energy
density of the light emitted from the light source, in response to
the output of the erythema sensor.
The present invention is also directed to an apparatus for treating
vascular lesions, comprising: a) a Dye laser unit; b) a vacuum
chamber placed on a skin target which is formed with an aperture on
the distal end thereof and provided with a clear transmitting
element on the proximate end thereof, said transmitted element
being transparent to light which is emitted from the laser unit and
directed to said skin target and being suitable for transmitting
the light in a direction substantially normal to a skin surface
adjoining said skin target; c) a handpiece which is connected to,
or integral with, said vacuum chamber, for directing light to a
skin target; d) a rim for sealing the peripheral contact area
between the skin surface adjoining said skin target and the wall of
the handpiece; e) a vacuum pump for applying a vacuum to said
vacuum chamber, the level of the applied vacuum suitable for
drawing said skin target to said vacuum chamber via said aperture;
f) a control unit for controlling operation of the vacuum pump and
laser unit; and g) means for modulating the applied vacuum by said
control unit in such a way that the concentration of blood and/or
blood vessels is increased within a predetermined depth below the
skin surface of said skin target, optical energy associated with
the directed intense pulsed light capable of being absorbed within
said predetermined depth and treating a vascular lesion.
The present invention also comprises an apparatus for evacuating
condensed vapors produced during the cooling of skin prior to
firing an intense pulsed light, comprising: a) a vacuum chamber
having a proximate end and positionable on a skin target such that
a gap is formed between the proximate end thereof and the skin
target, said proximate end being transparent to intense pulsed
light directed to said skin target and to targeted skin structures
located below the epidermis within the projected area of the
proximate end and suitable for transmitting the intense pulsed
light in a direction substantially normal to a skin surface
adjoining said skin target; b) means for skin cooling, said skin
cooling means adapted to reduce the rate of temperature increase of
the epidermis at the skin target; and c) means for applying a
vacuum to said vacuum chamber, the level of the applied vacuum
suitable for-- i. drawing said skin target to said vacuum chamber;
ii. increasing the concentration of blood and/or blood vessels
within a predetermined depth below the skin surface of said skin
target corresponding with the depth of said targeted skin
structures, optical energy associated with the directed intense
pulsed light being absorbed within said targeted skin structures;
and iii. evacuating condensed vapors which are produced within said
gap and condense on said proximate end during the cooling of
skin.
In one aspect, the skin cooling means is a metallic plate in
abutment with said vacuum chamber on the external side thereof and
positionable on the skin surface adjoining said skin target, said
plate being cooled by means of a thermoelectric cooler operative to
cool the lateral sides of the vacuum chamber.
In another aspect, the skin cooling means is a gel, a low
temperature liquid or gas applied onto the skin target.
The present invention is also directed to a method for treatment of
lesions by the absorption of light in targeted skin structures,
comprising the steps of: a) placing a U-shaped vacuum chamber which
is transparent to intense pulsed light and provided with two
opposed conduits on a skin target; b) applying a vacuum to said
vacuum chamber via a first conduit; c) increasing the vacuum level
within said vacuum chamber by occluding a second conduit, whereby
said skin target is drawn to said vacuum chamber and the
concentration of blood and/or blood vessels at a predetermined
depth below the skin surface of said skin target is increased; d)
firing the intense pulsed light source after a predetermined delay
following step c) such that intense pulsed light is directed to
targeted skin structures below said skin target, optical energy
associated with the directed intense pulsed light capable of being
absorbed within said predetermined depth and treating a lesion.
In one aspect, the second conduit is occluded by placement of a
finger thereon.
In one aspect, the method further comprises the steps of increasing
the pressure within the vacuum chamber to atmospheric pressure by
opening the second conduit and repositioning the vacuum
chamber.
The lesions are selected from the group of vascular lesions
including port wine stains, telangectasia, rosacea, spider veins,
unwanted hairs, damaged collagen, acne, warts, keloids, sweat
glands, and psoriasis.
The present invention also comprises a method for evacuating
condensed vapors produced during the cooling of skin prior to
firing an intense pulsed light, comprising: a) placing a U-shaped
vacuum chamber which is transparent to intense pulsed light and
provided with two opposed conduits on a skin target; b) chilling
the skin target; c) applying a vacuum to said vacuum chamber via a
first conduit; d) increasing the vacuum level within said vacuum
chamber by occluding a second conduit, whereby said skin target is
drawn to said vacuum chamber and the concentration of blood and/or
blood vessels at a predetermined depth below the epidermis of said
skin target is increased; e) firing the intense pulsed light source
after a predetermined delay following step d) such that intense
pulsed light is directed to targeted skin structures below said
skin target, optical energy associated with the directed intense
pulsed light capable of being absorbed within said predetermined
depth and treating a lesion. f) evacuating condensed vapors which
are produced within said gap during the cooling of skin prior to
firing an intense pulsed light.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 illustrates a side view of various laser units equipped with
a diffusing unit, in accordance with the present invention, wherein
the delivery system shown in FIG. 1a is an articulated arm, in FIG.
1b is an optical fiber and in FIG. 1c is a conical light guide;
FIG. 2 illustrates a side view of the distal end of a laser unit,
showing how the diffusing unit is attached thereto, wherein the
diffusing unit is externally attached to the guide tube in FIG. 2a,
is attached to a pointer in FIG. 2b, is releasably attached to the
guide tube in FIG. 2c, is integrally formed together with the guide
tube in FIG. 2d and is displaceable in FIG. 2e whereby at one
position the exit beam propagates therethrough and at a second
position the exit beam does not propagate therethrough;
FIG. 3 is a schematic diagram of various configurations of prior
art laser units, wherein FIG. 3a shows a non-scattered beam
directed by reflectors to a target, FIG. 3b shows a non-scattered
beam directed by an optical fiber to a target, FIG. 3c illustrates
prior art surgery performed with a laser beam and scanner, FIG. 3d
shows the propagation of prior art refracted laser beams towards a
blood vessel, FIG. 3e shows an ablative laser beam focused on
tissue in conjunction with a scanner, and FIG. 3f shows the
formation of a crater in tissue by an ablative beam;
FIG. 4 is a schematic diagram illustrating the advantages of
employing a diffusing unit of the present invention, wherein FIG.
4a shows the relative location of the diffusing unit, FIG. 4b shows
that a collimated laser beam is transformed into a randomly
scattered beam, FIG. 4c shows that a scattered beam reduces risk of
injury to the skin and FIG. 4d shows that a collimated laser beam
reduces risk of injury to the eyes;
FIG. 5 is a schematic drawing showing the propagation of a laser
beam towards a blood vessel, wherein FIG. 5a shows the propagation
of an unscattered laser beam towards a blood vessel, FIG. 5b shows
the propagation of a scattered laser beam towards a blood vessel,
FIG. 5c illustrates the formation of an ablation by means of an
unscattered laser beam. FIG. 5d illustrates the formation of an
ablation by means of an scattered laser beam in accordance with the
present invention, and FIG. 5e illustrates the scattering of a
laser beam distant from a blood vessel;
FIG. 6a is a schematic drawing showing the accumulation of liquid
residue on a diffusively transmitting element and FIG. 6b is a
schematic drawing in which a diffusively transmitting element is
shown to be mounted within a hermetically sealed diffusing
unit;
FIG. 7 illustrates the production of a plurality of microlenses,
wherein FIG. 7a illustrates the sandblasting of a metallic plate,
FIG. 7b illustrates the addition of a liquid sensitive to
ultraviolet light, FIG. 7c illustrates the removal of the metallic
plate and FIG. 7d illustrates the generation of a scattered laser
beam through the microlenses;
FIG. 8 illustrates two types of a diffusing unit, wherein FIG. 8a
illustrates one employing a single wide angle diffuser and FIG. 8b
illustrates one employing a small angle diffuser;
FIG. 9 illustrates a diffusing unit which employs a tapered light
guide, such that the light guide receives monochromatic light from
an optical fiber in FIG. 9a and from an array of microlenses in
FIG. 9b;
FIG. 10 illustrates a diffusing unit which utilizes an angular beam
expander without a light guide in FIG. 10a and with a light guide
in FIG. 10b;
FIG. 11 illustrates a diffusing unit which employs two holographic
diffusers, each of which is attached to a corresponding light
guide;
FIG. 12 illustrates a diffusing unit which includes two diffusers,
one of which is axially displaceable, wherein FIG. 12a illustrates
the unit in an active position and FIG. 12b in an inactive
position;
FIG. 13 is a schematic drawing of another preferred embodiment of
the present invention in which a scanner rapidly repositions a
coherent laser beam onto a plurality of targets on a diffusively
transmitting element;
FIG. 14 is another preferred embodiment of the present invention in
which a non-scattering diverging unit is used to diverge an input
laser beam, wherein FIG. 14a illustrates a single optical element
and FIG. 14b illustrates a plurality of elements;
FIG. 15 is a schematic diagram of various means of cooling skin
during laser-assisted cosmetic surgery, wherein FIGS. 15a-d are
prior art means, while FIG. 15e utilizes cooling fluid and FIG. 15f
utilizes a thermoelectric cooler;
FIG. 16 illustrates an eye safety measurement device;
FIG. 17 schematic drawing of a flashing device, wherein FIG. 17a
illustrates one that induces uncontrolled blinking before firing a
laser beam, FIG. 17b is a timing diagram corresponding to the
flashing device of FIGS. 17a, and 17c illustrates a flashing device
that detects a retroreflected beam from an eye within firing range
of a laser beam;
FIG. 18 is a schematic drawing which illustrates the propagation of
an intense pulsed laser beam from a handpiece to a skin target
according to a prior art method;
FIG. 19 is a schematic drawing which illustrates the propagation of
an intense pulsed non-coherent light beam from a handpiece to a
skin target according to a prior art method;
FIG. 20 is a schematic drawing of a prior art treatment method by
which pressure is applied to a skin target, in order to expel blood
from those portions of blood vessels which are in the optical path
of subcutaneously scattered light;
FIG. 21 is a schematic drawing of a prior art vacuum-assisted
rolling cellulite massage device;
FIG. 22 is a schematic drawing of a prior art vacuum-assisted hair
removal device adapted to reduce the blood concentration within a
skin fold formed thereby, in order to illuminate two opposed sides
of the skin fold and consequently remove melanin-rich hair
shafts;
FIG. 23 is a schematic drawing of apparatus in accordance with one
embodiment of the present invention, employing a manually occluded
U-shaped evacuation chamber;
FIG. 24 is a schematic drawing of apparatus in accordance with
another embodiment of the present invention, employing an
electronically occluded evacuation chamber;
FIG. 25 is a schematic drawing of apparatus in accordance with the
present invention, employing an intense pulsed non coherent light
source;
FIG. 26 is a schematic drawing of apparatus in accordance with the
present invention, which is provided with a skin chiller;
FIG. 27 is a drawing which schematically illustrates the effect of
applying a subatmospheric pressure to a vacuum chamber in order to
increase the blood concentration in skin drawn towards the vacuum
chamber;
FIG. 28 is a drawing which schematically illustrates the increased
concentration of a plurality of blood vessels in a skin target
following application of a vacuum to a vacuum chamber, resulting in
increased redness of skin and enhanced absorption of light;
FIG. 29 is a photograph illustrating the change in skin color
following treatment of a fine wrinkle by use of a vacuum assisted
handpiece in accordance with the present invention;
FIG. 30 is a schematic drawing of another embodiment of the
invention, illustrating propagation of intense pulsed light from an
external light source to a transparent modulated vacuum chamber;
and
FIG. 31 schematically illustrates another embodiment of the
invention which employs both an intense pulsed light source and a
radio frequency source, for improved coagulation of blood
vessels.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1a illustrates a high-intensity laser unit, generally
designated by 10, which is suitable for use with the present
invention. Laser unit 10 operates at a wavelength ranging between
300 and 1600 nm or between 1750 nm and 11.5 microns, either pulsed,
with a pulse duration of 1 nanosecond to 1500 milliseconds and an
energy density of 0.01.200 J/cm.sup.2, or continuous working with a
power density higher than 1 W/cm.sup.2. Laser unit 10 is provided
with a diffusing unit, generally designated by 15, which induces
the exit beam to be scattered. An exit beam is considered to be
scattered according to this embodiment when its average half angle
angular divergence is greater than 42 degrees relative to the
propagation axis of collimated beam 4. A half angle of 60 degrees
corresponds to the half angle generated by an "ideal transmitting
diffuser," which herein refers to a diffuser with 100% transmission
and is provided with Lambertian angular scattering properties. Such
a scattering angle, in accordance with the present invention,
allows the light which exits diffusing unit 15 to be safe to the
eyes of a bystander, yet is provided with a sufficiently high
energy density which is necessary for the clinical efficacy of the
laser unit.
Laser unit 10 comprises amplifying medium 1 activated by power
supply 2 for increasing the intensity of a light beam and two
parallel mirrors 3 that provide feedback of the amplified beam into
the amplifying medium, thereby generating a coherent beam of
ultrapure frequency. The laser unit emits a coherent beam 4 which
propagates through a delivery system 5 to distal end 6. The
delivery system depicted in FIG. 1a is articulated arm 7a.
Diffusing unit 15 is fixedly attached to the distal end of guidance
tube 12 by attachment means 16, which may be a set of screws or by
bonding or other means known to those skilled in the art, thereby
inducing non coherent randomly scattered beam 14 associated with a
narrow spectral bandwidth that does not present any risk of damage
to bodily tissue if the laser is inadvertently directed to an
incorrect target. The diffusing unit includes a passive refractive
element that preserves the wavelength of coherent beam 4, as well
as its narrow bandwidth, which is generally less than one
Angstrom.
In one preferred embodiment of the invention, diffusing unit 15 is
preferably cylindrical or rectangular, although any other
geometrical shape is equally suitable, and comprises diffusively
transmitting element 13, which is proximate to distal end 6 of the
laser unit and clear transmitting element 17. Both diffusively
transmitting element 13 and clear transmitting element 17 have the
same dimensions and are bonded to diffusing unit 15. Diffusively
transmitting element 13 and clear transmitting element 17 are
preferably separated by narrow gap 18. Due to the existence of gap
18, the laser beam will remain scattered even if clear transmitting
element 17 shatters, thereby preserving the inherent safety of a
laser unit that incorporates the present invention. The width of
gap 18 is as small as possible, usually 0.1 mm. However, diffusing
unit 15 may be adapted to a configuration in which diffusively
transmitting element 13 contacts clear transmitting element 17.
Alternatively, diffusing unit may be provided without a clear
transmitting element, whereby the frosted surface of diffusively
transmitting element 13 faces the laser unit and its smooth surface
faces the tissue.
Scattering is achieved by means of minute irregularities of a
non-uniform diameter formed on the substrate of diffusively
transmitting element 13. Diffusively transmitting element 13 is
preferably produced from thin sand blasted or chemically etched
glass, e.g. having a thickness from 0.1 to 0.2 mm, or a thin sheet
of non-absorbing light diffusing polymer, e.g. having a thickness
of less than 50 microns, such as light diffusing polycarbonate,
Mylar or acrylic.
A diffusively transmitting element may also be produced by using a
large angle holographic diffuser such as one produced by Physical
Optics Corporation (PCO), USA, and is placed adjacent to an
additional diffuser. A holographic diffuser illustrated in FIG. 11
induces a scattering half angle, for example, of at least 40
degrees and the second diffuser additionally induces the scattering
so as to attain a scattering half angle of e.g. 60 degrees.
A diffuser which approaches an ideal transmitting diffuser and
induces a scattering half angle of 60 degrees and a scattering
solid angle of 3.14 sr may be produced from material such as
acrylic or polycarbonate by pressing the material against an
appropriate surface provided with a very dense array of Frensnel
microlenses, such as those produced by Fresnel Technologies Inc.,
USA, or by placing arrays of microlenses surfaces separated from a
light guide as depicted in FIG. 9b.
Similarly diffusively transmitting element 13 may be produced from
light diffusing paper such as transparent "Pergament" drawing
paper, and may also be produced from other materials such as ZnSe,
BaF.sub.2, and NaCl, depending on the application and the type of
laser used. Both faces of clear transmitting element 17 are
essentially planar and smooth. Clear transmitting element 17, which
is capable of withstanding the thermal stress imposed by a
scattered laser beam, is transparent and made from sapphire, glass,
a polymer such as polycarbonate or acrylic, and may be produced
from other materials as well, such as ZnF.sub.2.
Diffusively transmitting element 13 may be chilled so that it will
be capable of withstanding the high power densities which are
necessary for attaining clinical efficacy.
As depicted in FIG. 1b, the delivery system may also be optical
fiber 7b into which laser beam 4 is focused. Diffusing unit 15 is
mounted on guidance tube 8, which directs the beam exiting the
distal end of optical fiber 7b by attachment means 16. Furthermore,
as depicted in FIG. 1c, the laser unit may be comprised of array 11
of miniature lasers, such as those provided with high power diode
lasers, e.g. the Lightsheer produced by Coherent, USA, for hair
removal. The beam delivery system for this configuration is
preferably conical reflector 7c. In this configuration, diffusing
unit 15 is fixed to distal end 6 of light guide 7c and transforms a
high-risk beam into randomly scattered beam 14.
FIG. 2 illustrates various methods by which diffusing unit 15 is
attached to a laser unit. In FIG. 2a, bracket 19 which supports
diffusing unit 15 is attached to guidance tube 12 of an existing
laser unit, such as one in use in a clinic, by attachment means
16a, which may be a set of screws or by bonding. As shown in FIG.
2b the laser unit is provided with pointer 31, or any other
equivalent subdiffusing unit which enables the user to direct beam
4 to a desired target on the skin, by the focal length and beam
diameter which are dictated by lens 9 mounted within guidance tube
12. In this alternative, diffusing unit 15 may be externally
attached to guidance tube 12, or may be attached to pointer 19. In
FIG. 2c, diffusing unit 15 is attached to Velcro tape 16c, or
another type of adhesive tape. This type of attachment means is
sufficient for temporary usage. In FIG. 2d, diffusing unit 15 is
integrally formed together with guidance tube 12 during
manufacturing, internal to the outer wall thereof. FIG. 2e
illustrates a releasable attachment means, whereby in one position
of a displaceable diffusing unit the exit beam is coherent, not
propagating through a diffusively transmitting element, and in a
second position in which diffusing unit 15 is attached to guidance
tube 12, the exit beam is noncoherent and propagates through a
diffusively transmitting element.
In prior art cosmetic laser surgery, as shown in FIG. 3a, laser
unit 20 emits a non-scattered coherent beam 24 from distal end 23
via reflectors 21, 22, by optical fiber 29 in FIG. 3b, or
alternatively by deflectors 27 as shown in FIG. 3c, to site 26 that
is to be treated within tissue 25. Following the surgery, a
well-defined spot is generally produced having a size of up to 20
mm, depending on the specific application and device. Furthermore,
beam 24 may be directed by means of motor 28 as shown in FIG. 3c in
those situations in which extensive surgery is desired and tissue
25 needs to be scanned. When the wavelength ranges from 310-1600
nm, i.e. ultraviolet and near-infrared, the beam is scattered into
individual rays 30, as shown in FIG. 3d, while propagating to blood
vessel 32 from site 26. Blood vessel 32 is presented as an example
and could be replaced by a hair follicle or any type of skin
lesion. At wavelengths ranging from 1750 nm to 11.5 microns, i.e.
far infrared, lasers are often used in focused pin-point ablation,
that is, having a diameter ranging from 50-200 microns at a shallow
depth of 20-150 microns, of epidermal or papillary dermal tissue in
conjunction with a scanner, as shown in FIG. 3e. The lasers are
used mainly for ablation of tissue, the formation of a crater shown
in FIG. 3f. Laser 20, which is capable of effecting the desired
surgery at a large distance between distal end 23 and target site
26 for the various applications shown in FIGS. 3a-d, nevertheless
can cause severe damage if the beam is not properly aimed.
In contrast, the present invention, which is schematically depicted
in FIG. 4, presents a much lower risk to the patient and to
observers. As shown in FIG. 4a, diffusing unit 15 is attached to
distal end 23 of the laser unit. Diffusing unit 15 transforms the
coherent, usually collimated laser beam 24 into homogeneous,
randomly scattered beam 14 shown in FIG. 4b. As a result beam 14
significantly reduces risk of injury to the skin as shown in FIG.
4c or to the eyes as shown in FIG. 4d since a collimated beam is
not directed to these parts of the body. At very short distances of
less than one tenth of the diameter of beam 24 from distal end 23,
beam 24 has not begun to completely scatter and increase its
diameter and is therefore efficacious as a means for performing
cosmetic surgery as shown in FIG. 4c, although an increase in the
laser power level may sometimes be needed to compensate for reverse
reflections from the diffusing unit into the laser unit.
Compensation, in terms of an increase in the needed power level for
the laser unit, for reverse reflections is usually be close to 16%
due to four air-glass interfaces with 4% Fresnel reflection, and at
times may attain 50%. An anti-reflection coating may be used to
reduce reflection. For laser units which operate at approximately
10-20% of their maximum energy capacity, it is possible to place
the exit plane of the diffusing unit, whether a frosted or clear
transmitting element, at a distance from the skin corresponding to
approximately 50% of the exit beam diameter.
FIG. 5 demonstrates the advantages of the present invention. FIG.
5a illustrates conventional coherent laser beam 24 at a wavelength
of 308 to 1600 nm. The collimated beam contacts tissue 25 at a
diameter of D before being scattered into individual rays 30 during
propagation to target destination 32. FIG. 5b illustrates the
result of attaching diffusing unit 15 to the laser unit. When
diffusing unit 15 is disposed at a small distance from the tissue
surface, the diameter of the scattered beam which contacts tissue
25 is increased by a negligible value of .DELTA.d, assuming uniform
scattering, in comparison with the original beam diameter of D. If
the thickness t of diffusing unit 15 is less than one-tenth of
original beam diameter D, there will be a loss of less than 20
percent in the original beam energy density. Also, the refraction
angle .theta., corresponding to an index of refraction of 1.5 for
keratin, into the tissue relative to collimated beam 24, when a gap
exists between diffusively transmitting element 13 and clear
transmitting element 17, will never exceed the critical angle of 42
degrees. At a refraction angle less than this critical value,
possible additional scattering in tissue is minimized. Consequently
light intensity within the tissue is preserved, therefore generally
retaining the clinical efficacy, i.e. the ability to perform a
surgical or cosmetic procedure, of the laser unit.
Just as superficial ablation 29 is formed in tissue 25 as a result
of a high energy density beam in the 1.8 to 11.5 micrometer
spectral range as shown in FIG. 5c, a similar ablation may be
formed in tissue 25 with the use of diffusing unit 15, with the
addition of .DELTA.d, as shown in FIG. 5d. A thin spacer (not
shown) may be advantageously added in order to evacuate vapors or
smoke that has been produced during the vaporization process. Such
a spacer is e.g. U-shaped in vertical cross-transmission element,
to allow for contact with a target at its lateral ends and for
vapor evacuation along the gap formed by its central open region.
For surgical procedures with which a very fast ablation rate is
needed, e.g. 1 cm.sup.3/sec for a skin thickness of 0.1 cm, the
spacer is necessarily relatively thick and the gap between the
ablated tissue and the diffusing unit is relatively large, e.g.
approximately 20-30 mm.
When an excessive amount of smoke is produced and the exit beam
becomes diffracted before impinging on the tissue, it may be
necessary to add a relay optics device (not shown), which
regenerates the degraded exit beam between the diffusing unit and
the tissue. An optical regenerator is provided with an internal
coating, such that a new and stronger beam with the same
characteristics as the degraded beam is produced when the coating
emits light energy when stimulated by the incoming photons of the
degraded beam. Cylindrical or conical tubes internally coated with
gold with an inlet diameter equal to the exit diameter of the
diffusing unit are exemplary optical regenerators for this
application. A small smoke evacuation port is preferably drilled in
the wall of the tube.
When a long-wavelength laser, which does not focus on an eye retina
and ranges from approximately 1345 nm to 10.6 microns, is employed,
an diffusing unit may not be needed. To scatter the exit beam, an
element may be externally attached to a surface which is in contact
with the skin during a cosmetic or surgical procedure, so that the
exit beam will diverge to a large extent and ensure eye safety from
a distance of a few cm from a target, while the energy density is
sufficiently high enough to allow for clinical efficacy. For
example, a miniature 0.21 Joule/pulse Erbium laser, which produces
a spot size of 1 mm.sup.2 and generates an energy density of 2.1
J/cm.sup.2, greater than the threshold for tissue ablation, will be
safe to the eyes from a distance of 10 cm from a target if the beam
has a divergence half angle of 45 degrees.
While the laser is an effective surgical tool when the diffusing
unit is very close to the tissue surface, safety is ensured after
the diffusing unit is repositioned so that it is disposed at a
distance of a few millimeters, depending on the laser energy, from
the tissue surface. As shown in FIG. 5e, the energy density of
scattered beam 14 which impinges upon the surface of tissue 25 is
much less than the energy density which results when the diffusing
unit is proximate to the tissue surface.
The diffusing unit is adapted to induce random scattering despite
any adverse external conditions encountered during the surgical
procedure.
The most likely cause of a potential change in rate of scattering
of the laser beam passing through diffusing unit 15 results from
contact with tissue. Following a surgical procedure in which the
diffusing unit contacts tissue, liquid residue 36, such as sebum,
water and cooling gel, as shown in FIG. 6a, may accumulate on
diffusively transmitting element 13. The refractive index of liquid
residue 36 may be such that, in combination with the refractive
index of diffusively transmitting element 13, refracted beam 38
approaches the pattern of collimated beam 24 that impinges on the
diffusing unit.
To minimize the risk of injury which may exist if the refracted
beam is nearly collithated, diffusively transmitting element 13 is
mounted within diffusing unit 15, which is preferably hermetically
sealed with sealing element 39 as shown in FIG. 6b, to prevent the
accumulation of liquid residue on the former. Clear transmitting
element 42 is attached to the distal end of diffusing unit 15 by
adhesion and by means of a spacer (not shown), and is separated
from diffusively transmitting element 13 by air gap 41. Clear
transmitting element 42 and diffusively transmitting element 13 are
mutually parallel, and both are perpendicular to the longitudinal
axis of diffusing unit 15. When the air gap is less than a
predetermined value, a corresponding increase in beam diameter due
to scattering is limited, thereby ensuring a minimal effectiveness
of the radiation carried by the laser beam for clinical
applications. It would be appreciated that accumulation of liquid
residue on clear transmitting element 42 will not compromise the
inherent safety of a laser unit equipped with a diffusing unit.
Since scattering occurs at diffusively transmitting element 13, and
the combined index of refraction of air gap 41, clear transmitting
element 42 and liquid residue is not sufficient to cause the
scattered beam to be once again collimated, the inherent safety of
the laser unit is preserved. The accumulation of liquid residue
will not affect the clinical efficacy of the laser unit since clear
transmitting element 42 is held close to a target during a surgical
procedure.
An additional advantage resulting from the separation of clear
transmitting element 32 from diffusively transmitting element 13
relates to added safety. Even if clear transmitting element 42 is
broken, diffusively transmitting element 13 will scatter the laser
beam.
A diffusively transmitting element, adapted to achieve diffusing
half angles greater than 45 degrees and as close as possible to an
ideal transmitting diffuser, which generates a half angle of 60
degrees, may be produced in several ways: Sandblasting the surface
of a plate of glass, sapphire, acrylic or polycarbonate with fine
particles having a size ranging from 1 to 200 microns, depending of
the wavelength of the laser beam, comprised of, by example,
aluminum oxide; Sandblasting the surface of a mold plate with fine
particles having a size ranging from 1 to 200 microns, depending on
the wavelength of the laser beam, comprised of, by example,
aluminum oxide and reproducing the contour of the newly formed mold
plate surface by pressing hot acrylic, or other suitable material
thereon; Etching the surface of a glass or sapphire plate by
chemical means, such as with hydrogen fluoride; Etching the surface
of a glass plate with a scanned focused CO.sub.2 laser beam;
Applying a thin sheet of light-diffusing polymer, such as a
polycarbonate sheet, a light diffusing acrylic plate, Mylar high
quality wax paper or graphical "Pergament Paper" to a glass plate;
Generating a diffraction pattern on the surface of a glass or on a
sheet of acrylic or polycarbonate by means of a holographic process
to thereby control the divergence angle through the diffraction
pattern, which is preferably as large as a half angle of at least
40-45; Providing a randomly distributed array of thin fibers,
arranged e.g. in the form of a conical fiber bundle light
concentrator, such as that produced by Schott, Germany, whose
aperture is provided with an exit half angle of greater than 40
degrees.
FIG. 7 illustrates the scattering effect that is achieved by
sandblasting. As shown in FIG. 7a, metallic plate 50 is bombarded
with aluminum oxide particles 48, thereby creating a random
distribution of craters 51, each of which having a different size.
Liquid 52, which is sensitive to ultraviolet light, is spilled on
metallic plate 50 in FIG. 7b and polymerized by ultraviolet
radiation. After removal of plate 50, for reuse in the next
production batch, transparent frosted plate 53 is produced, as
shown in FIG. 7c covered on one side with a random distribution of
convex lenses 55 of miniature size. Lenses 55, which have a very
short focal length of approximately a few wavelengths, convert a
collimated laser beam into a strongly divergent beam with a
complete loss of coherence. It is possible to use a similar
technique to produce a surface with convex or concave microlenses
57, as shown in FIG. 7d. Microlenses may be produced as well by
pressing melted acrylic onto a multimicrolens mold, instead of
using a UV curing technique.
As described above, an exit beam from a laser unit is randomly
scattered by a diffusing unit. One type of a diffusing unit is a
single wide angle diffuser as shown in FIG. 8a and comprises a
diffusively transmitting element 781 which produces scattered light
782 from laser beam 780 having a wide diffusing angle of T. Another
type of diffusing unit is shown in FIG. 8b, wherein wide angle
diffusion is attained by using divergent optical element 783, and
at least one diffuser 784 and refractive/reflective element 785.
With this type of diffusing unit, a wide diffusing angle of T is
generated in three stages: optical element 783 produces wide angle
divergent beam T.sub.1 from laser beam 780, diffuser 784 produces a
small diffusing angle of T.sub.2, and refractive/reflective element
785 expands angle T.sub.2 to achieve wide diffusing angle T. Such a
multi-component diffusing unit may achieve a wide diffusing angle
with the use of elements of high thermal resistance and durability.
It will be appreciated that refractive/reflective element 785 may
not necessarily be distally disposed with respect to diffuser 784,
and may be configured in any other way in order to achieve wide
diffusing angle T.
FIG. 9 illustrates another preferred embodiment of a diffusing
unit, designated as numeral 200. Diffusing unit 200 is a wide angle
diffusing unit, i.e. one that generates a scattering angle that
approaches that of an ideal transmitting diffuser, yet is capable
of enduring high power laser levels by using glass made of small
angle diffusers. Such a diffusing unit is advantageously employed
in those applications for which high energy densities are needed
for clinical efficacy, and accordingly only a wide-angle scattering
angle can ensure eye safety.
As depicted in FIG. 9a, optic fiber 201 is disposed adjacent to the
proximate end of tapered light guide 202, such that light rays 203
that exit from fiber 201 with half angle divergence A impinge the
inner wall of light guide 202. Rays 203 then are reflected from the
inner wall of the light guide at an increasingly smaller reflection
angle R. The inner wall is coated with a reflective coating so that
reflection angle R will be less than the critical angle for total
internal reflection. The tapering angle and the dimensions of the
light guide as well as the distance of the fiber from the light
guide are selected so that exit half angle C of diffused light 208
which propagates from distal end 204 of the light guide is at least
60 degrees. Also, the distance between fiber 201 and distal end 204
is selected so that the energy density of rays 207 emitted from
fiber 202 to distal end 204 without any reflection from the light
guide wall will be sufficiently low to be considered eve safe when
scattered from small angle diffuser 205, e.g. 10 degrees, which
induces a relatively small scattering angle and is proximately
placed with respect to distal end 204 of the light guide. A small
angle diffuser is advantageously selected due the availability of
such diffusers, its high durability and capability to withstand a
high energy density, as required for aesthetic and industrial
applications. Small angle diffuser 205 increases the divergence of
difused light 208, in addition to the divergence generated by
tapered light guide 202.
In an exemplary diffusing unit, fiber 201 induces a half angle
divergence of 25 degrees, the distance from fiber 201 to light
guide 202 is 16 mm, the inner diameter of light guide 202 at its
proximate end is 15 mm, the tapering angle of light guide 202 is 3
degrees, and the length of light guide 202 is 142 mm.
Diffusing unit 200 may also include a second light guide (not
shown) which receives diffused light 208 from the distal end of
light guide 202. This second light guide is sufficiently long so
that diffused light 208, which propagates from small angle diffuser
205, will be emitted from the entire surface of the exit plane of
the second light guide. The exit plane of the second light guide
therefore functions as an extended diffused source. For example, a
second light guide having a length of 50 mm and a small angle
diffuser which induces a scattering angle of 10 degrees will enable
diffused light to span a diameter of greater than 5 mm at the exit
of the second light guide.
As shown in FIG. 9b, diffusing unit 200 comprises array of
microlenses 210, instead of an optic fiber as in FIG. 8a, which is
disposed adjacent to the proximate end of tapered light guide 202.
Array 210 is configured such that light rays 203 that exit
therefrom with half angle divergence A impinge the inner wall of
light guide 202.
FIG. 10 illustrates diffusing unit 700, which comprises another
type of angular beam expander, namely one which comprises a set of
concave and convex mirrors. Small angle fiber 701 from which light
rays 703 exit with a small half angle divergence A, such as 5
degrees, is advantageously employed since diffuser unit 700
provides a high angular amplification.
As shown in FIG. 10a, half angle divergence A is selected so that a
light ray 703 impinges on convex mirror 702 and is reflected
therefrom to concave mirror 705. A ray 703 is further reflected
from mirror 705 at an angle that enables it to impinge upon, and be
scattered by, diffusively transmitting element 710, which is
affixed to concave mirror 705. In FIG. 10b, diffuser unit 700 is
additionally provided with light guide 715. The light which exits
from diffusively transmitting element 710 is received by light
guide 715 and is reflected within its inner wall, resulting in wide
angle diffusing from the entire exit surface of light guide 715.
Light guide 715 therefore functions as an ideal extended diffused
light source.
FIG. 11 illustrates a diffuser unit in which two 40.45 degrees
holographic diffusers 220 and 221 are attached to light guides 222
and 223, respectively. Each holographic diffuser induces a half
angle divergence of approximately 45-50 degrees. In order to
increase the divergence, two holographic diffusers are used. Light
rays 218 propagating from a monochromatic light source are
scattered by diffuser 220 to a half angle of D and then are
reflected within the inner wall of light guide 222. The scattered
light rays are further scattered by diffuser 221 to a half angle of
E, are reflected within light guide 223, and exit the diffuser unit
at a half angle of F, which approaches 60 degree, the value
corresponding to an ideal transmitting diffuser. The light guides
are chilled so that the holographic diffusers, which are usually
made from plastic material, will also be chilled so that they will
be able to withstand the high thermal stress imposed by a high
power laser beam. Each light guide may be solid or hollow, and may
be made from glass, sapphire, a liquid dielectric, or plastic.
FIG. 12 illustrates another preferred embodiment of the invention
in which diffuser unit 300 comprises two distinct diffusers 301 and
302, wherein at least one is axially displaceable. FIG. 12a
illustrates diffuser unit 300 in an active position, such that
diffusers 301 and 302 are essentially in contact with each other.
When in an active position, diffusers 301 and 302 act as a singular
randomly scattering diffuser, since substantially all of the
monochromatic light 305 that impinges on diffuser 301 is
transmitted to diffuser 302. Although the energy density needed for
performing an efficacious treatment with monochromatic light 305 is
minimally affected, a slight increase of the laser energy can
compensate for any energy density losses. FIG. 12b illustrates
diffuser unit 300 in an inactive position, such that diffusers 301
and 302 are separated from each other by a distance L, which is
sufficiently long to ensure that the radiance of the scattered
light which exits diffuser 301 and is additionally scattered by
diffuser 302 is below a level that is safe to one's eyes.
As shown, diffuser 301 is axially displaceable by means of a
plurality of springs 308 that connect diffuser mount 301a to
diffuser mount 302a. When lever 315, which is connected to diffuser
mount 301a, is depressed springs 308 are compressed and diffuser
301 becomes substantially in contact with diffuser 302, as shown in
FIG. 12a. Distal end 317 of handpiece 303 is then brought in
contact with a skin location to be treated by monochromatic light
305 having a high energy density and a high radiance. Upon
completion of a desired surgical or cosmetic procedure, lever 315
is released and springs 308 are biased to separate diffuser 301
from diffuser 302 by a distance of L, as shown in FIG. 12b, whereby
the radiance of the scattered light is below a safe level. It will
be appreciated that any other means well known to those skilled in
the art for axially displacing one or more of the diffusers may be
used.
FIG. 13 illustrates an embodiment of the present invention by which
tissue, having a larger surface area than the area of the beam
impinging thereon, may be treated without overexposure to a laser
beam. In prior art systems using a scanner, the treatment beam is
quickly displaced in a programmable fashion from one location to
another on the tissue to be treated. Although this method provides
rapid and reliable treatment, there is a significant risk, however,
that the laser beam is liable to be aimed at eyes, skin or
flammable materials located in the vicinity of the laser unit.
The diffusing unit generally designated by 60 is shown. In this
embodiment the diffusing unit is rigidly attached to delivery
system 61, which is provided with a scanner. Diffusively
transmitting element 63 is formed with a plurality of visible
targets 66 and is placed close to the skin, facing the distal end
of delivery system 61. Diffusing unit 60 is preferably provided
with a clear transmitting element, as described hereinabove.
Coherent collimated or convergent exit beam 64 is directed via a
plurality of repositionable reflectors 65 to a predetermined target
66 graphically indicated on diffusively transmitting element 63.
The beam that impinges upon a predetermined target 66 is randomly
scattered and converted into non-coherent beam 67 whose energy
density is essentially similar to that of exit beam 64. Reflectors
65 are controllably repositionable by means of a scanner, whereby
they may be displaced from one position and angular disposition to
another, so as to accurately direct exit beam 64 to another target
66. The sequence of which target is to receive exit beam 64 after a
selected target is programmable and is preferably semi-random to
reduce pain which may be felt resulting from the treatment of two
adjacent targets, with the time increment between two doses of
laser treatment being less that less than a preferred value. A
programmable sequence precludes on one hand the chance of a target
not to receive an exit beam at all, and on the other hand precludes
the chance of not to be inadvertently exposed twice to the exit
beam. With the usage of diffusing unit 60, small-diameter beams,
e.g. 0.1-7.0 mm, may be advantageously employed to treat a tissue
having an area of 16 cm.sup.2. Similarly, a scanner may be employed
for any other feasible wide-area diffusing unit, such as an array
of diffusers/light guides incorporating those units illustrated in
FIGS. 9-12, whereby an exit laser beam may be directed to each of
the diffusers/light guides. Such an array may consist of 9
diffuser/light guides, each having a 3-mm diameter, to cover an
area of 81 mm.sup.2. Scanning may also be achieved by laterally
moving an angular expander over the diffuser/light guide array.
FIG. 14 illustrates another preferred embodiment of the invention
in which a diffusing unit is not used, but rather a diverging
optical element is employed to produce an exit beam having
radiance, or alternatively, energy density, depending on the
wavelength, below a safe level.
As shown in FIG. 14a, diverging optical element 741 is placed in
diverging unit 748, which is attached to the distal end of the
laser unit by any means depicted hereinabove in FIG. 2. Divergent
element 741, which is provided with a relatively short focal
length, focuses input beam 740 at point F. The beam diverges at a
point distally located with respect to point F, as well known to
those skilled in the art, and produces divergent beam 742 having a
divergent angle of H, a cross section 743 at a plane coplanar with
distal end 744 of diverging unit 748 and a cross section 752 at a
plane coplanar with shield 750. When divergent beam 742 has a cross
sectional dimension at least equal to cross section 752, its
radiance is less than an eye safe level.
Pulsed laser radiation in the wavelength range of 1400 nm to 13
microns, according to the ANSI Z 136.1 standard, is considered eye
safe if the Accessible Energy Limit (AEL) at the ocular plane is
less than a value of 0.56*t**(1/4) J/cm.sup.2, where t is the pulse
duration in seconds. For example, a typical pulse duration ranging
from 1 to 100 msec is associated with an AEL ranging from 0.1 to
0.3 J/cm.sup.2, respectively. Accordingly, diverging unit 748 is
provided with at least one shield 750, each of which prevents one's
head from entering a zone of the divergent beam at which the energy
density is greater than the AEL. Shield 750 is connected to tube
746 of diverging unit 748 by means of rigid member 747, and cross
member 749. The length of cross member 749 and the degree of
angular divergence H is selected to ensure that the energy density
distal to shield 750 is less than the AEL. Normally, cross member
747 is unyielding to head pressure, thereby ensuring eye safety.
However, when a lever is actuated, for example, cross member 747 is
opened and a spring (not shown), which is normally in a relaxed
state and connected to both rigid member 747 and cross member 749,
becomes tensed and allows the shield to be proximately displaced.
When shield 750 is proximately displaced, distal end 744 of
diverging unit 748 may be in contact with a target skin location
and cross section 743 of beam 742 having a sufficiently high energy
density for a desired application may be utilized. For example,
diverging unit 748 is suitable for those applications by which a
laser beam is greatly absorbed by water.
FIG. 14b illustrates diverging unit 950, which comprises array 991
of focusing lenslets each of which has a diameter of e.g. 0.7 mm,
array 992 of lenses each of which is provided with reflective
coating 993 on its distal side, and a plurality of convex
reflectors 995 attached to transparent plate 994. Rays 990 from a
collimated laser beam are focused by lenslets 991 and transmitted
through non-reflective area 999 formed on the distal side of each
lens 992. The location of each non-reflective area 999 is selected
so that a focused ray propagating therethrough will impinge upon a
corresponding reflector 995 at such a reflecting angle such that it
will be reflected therefrom and strike a corresponding reflective
coating 993, from which it is again reflected and propagates
through transparent plate 994. Most rays, such as ray 996 then exit
plate 994. However, some rays, such as ray 989, strike a
transversal side 997 of plate 994, which is provided with a
reflective coating and causes these rays to exit plate 994. Plate
994 accordingly functions as a light guide when transversally
reflecting light rays strike a side 997. The length, i.e. the
distance between sides 997, of plate 994 is substantially equal to
the length of array 991, and therefore the energy density of an
input beam is preserved at the exit of plate 994. In order to
comply with the requirements of the aforementioned standards,
namely to achieve a safe radiance level with a lens having a
diameter of 0.7 mm and producing a divergent half angle of 60
degrees, a lenslet 991 with a focal length of 3 mm may be used to
achieve a uniform radiance at a solid angle of approximately .PI.
steradians.
The distal end of plate 994 may be etched to further diffuse the
divergent light exiting therefrom, so that the distal end may
function as an extended diffused light source. If desired, the
transparent plate may be substituted by a light guide.
In summation, the present invention incorporates four groups of
units which cause a monochromatic light to diverge at a
sufficiently wide angle so that the radiance of an exit beam is eye
safe:
1) A diverging unit provided with a single diverging optical
element;
2) A multi-component diverging unit provided with reflective and
refractive optical elements, and without any diffusers;
3) A diffusing unit provided with a single thin diffusively
transmitting element; and
4) A multi-component diffusing unit, whereby a wide divergent,
diffusing angle is achieved by using a high thermally resistant
refractive/reflective optical component, as well as at least one
thermally resistant low angle diffuser.
When a multi-component diffusing or diverging unit is employed, a
relatively simple eye safety monitoring device can be used. Due to
the high thermal durability of the selected multi-component unit,
the radiance homogeneity is essentially preserved from the
proximate end to the distal end thereof. Consequently, limited
sampling of the radiance level is required, and an expensive
monitoring device is rendered unnecessary. Another advantage of a
multi-component unit is that monochromatic light reflected from the
skin returns to the corresponding unit via a light guide with
respect to a diffusing unit and via a transparent plate with
respect to a diverging unit, preventing an adverse effect to the
skin if reflected monochromatic light were to return thereto.
FIG. 15 illustrates another preferred embodiment of the invention
in which a diffusing unit is provided with a skin cooling system.
Transparent skin cooling devices are often used in conjunction with
skin laser treatments. However they do not scatter laser light and
do not reduce the risks associated with exposure to a laser beam.
FIGS. 13a-d illustrate prior art skin coolers. In FIGS. 15a and 15b
transparent lenses or plates 80 are in contact with tissue 79.
Cooling liquid 81, which flows through conduit 83, conducts heat
from the heated skin to a cooler. Treatment laser beam 82
propagates without being scattered through the cooling device and
penetrates the skin. In FIG. 15c gaseous coolant 84 is used. In
FIG. 15d, highly conductive plate 86 is in contact with tissue 79
and chilled by thermoelectric cooler 85.
As shown in FIG. 15e, diffusing unit 75 comprises diffusively
transmitting element 74, clear transmitting element 70 and conduit
71 formed therebetween. Conduit 71 is filled with a low temperature
gas or liquid of approximately 4.degree. C., which enters conduit
71 through opening 72 and exits at opening 73. The cooling fluid
preferably flows through a cooler (not shown). Diffusing unit 75 is
positioned in contact with the skin, for treatment and cooling
thereof. Clear transmitting element 70 is preferably produced from
a material with a high thermal conductivity such as sapphire, in
order to maximize cooling of the epidermis. Diffusively
transmitting element 74 is disposed such that its proximal face is
frosted side and its distal face is planar, facing conduit 71. In
FIG. 15f, the diffusing unit comprises diffusively transmitting
element 74 made from sapphire, which is chilled at its lateral
sides 75 by thermoelectric cooler 76. The proximal side of 74 is
frosted and the smooth distal side faces the skin. The parameters
of the flowing fluid and of the cooler are similar, by example, to
the Cryo 5 skin chiller produced by Zimmer, Calif., USA. It will be
appreciated that any of the skin cooling means illustrated in FIGS.
15d-f may be used to cool skin which is heated as a result of the
impingement of monochromatic light thereon even though a
diffusively transmitting element is not used.
The eye safety when exposed to the exit beam of a diffusing or
diverging unit is significantly improved relative to prior art
devices.
Parameters for eye safety analysis are presented in "Laser Safety
Handbook," Mallow and Chabot, 1978 in which the standard ANSI Z
136.1 is cited. A laser beam which is reflected from a light
diffusing surface is categorized as an extended diffused source if
it may be viewed at a direct viewing angle A, greater than a
minimum angle Amin, with respect to a direction perpendicular to
the source of the laser beam. If a reflected beam may not be viewed
at angle A, it is categorized as an intrabeam viewing source. Since
a reflected beam is more collimated when viewed at a distance,
viewing conditions are intrabeam if the distance R from the source
of the laser is greater than a distance Rmax.
Another significant parameter is the maximum permitted radiance,
normally referred to as Accessible Energy Limit (AEL) while staring
at a diffusing surface which completely reflects a laser beam. AEL
depends on the energy density, exposure duration, and wavelength of
the laser beam, as well as the solid angle into which the laser
beam is diffused. The safety level of a laser unit is evaluated by
comparing the AEL to the actual radiance (AR) of the laser beam.
Staring at the exit of a diffusing unit according to the present
invention is equivalent to staring at a reflecting extended
diffuser with 100% reflectivity. The AEL for visible and near
infrared radiation exiting a diffusing unit for which protective
eyeglasses are unnecessary based on an extended diffuser source is
defined by ANSI Z 136.1, as 10*k1*k2*(t^1/3) J/cm.sup.2/sr, where t
is in seconds and k1=k2=1 for a wavelength of 400-700 nm, k1=1.25
and k2=1 at 750 nm, k1=1.6 and k2=1 at 810 nm, k1=3 and k2=1 at 940
nm and k1=5 and k2=1 at a wavelength of 1060 to 1400 mm. The safety
limit set by ISO 15004: 1997 E for pulsed radiation is 14
J/cm.sup.2/sr.
The actual radiance (AR) is the actual energy per cm.sup.2 per
steradian emitted from a diffusing unit. The ratio between AEL and
AR indicates the safety level of the laser unit employing a
diffusing unit, according to the present invention. A ratio less
than 1 is essentially unsafe. A ratio between 1.0 and 5 is similar
to that of high intensity flashlight sources used in professional
photography and intense pulsed light sources used in aesthetic
treatments, and is much safer than prior art laser sources. Prior
art laser sources which do not incorporate a diffusing unit have a
ratio which is several orders of magnitudes less than 1.
Table I below presents a comparison in terms of eye safety between
the exit beam of monochromatic light after being scattered by a
diffusing unit into a solid angle of 3.14 sr, which is equivalent
to that attained by an ideal transmitting diffuser, according to
the present invention. The parameters for a non-coherent
diode-based laser unit are based on one produced by Dornier
Germany. The parameters for a non-coherent Alexandrite-based laser
unit are based on one produced by Sharplan/ESC (Epitouch). The
parameters for a non-coherent Nd:YAG-based laser unit intended for
hair removal are based on one produced by Altus, USA. The
parameters for a non-coherent Nd:YAG-based laser unit intended for
photo-rejuvenation are based on one produced by Cooltouch, USA. The
parameters for a non-coherent dye-based laser unit are based on one
produced by ICN (Nlight). The parameters for an intense pulsed
light laser unit are based on one produced by ESC. The AEL for a
particular wavelength and pulse duration is based on the
aforementioned ANSI Z 136.1 standard.
TABLE-US-00001 TABLE I Non coherent Non coherent Non coherent CW
Diode Non coherent Alexandrite Nd: YAG Nd: YAG Non coherent Intense
Pulsed 60 degrees System type Diode based based based based Dye
based Light diffuser Application Hair removal Hair removal Hair
removal Photo- Photo- Hair removal Tooth re juvenation re
juvenation whitening Parameters Wavelength 940 nm 755 nm 1064 nm
1320 nm 585 nm 645-900 nm 980 nm Energy 6 J 10 J 11.3 J 7 J 0.6 J
90 J 1.5 J Pulse duration 50 msec 40 msec 60 msec 60 msec 0.5 msec
40 msec 1 sec Spot size 5 mm 7 mm 6 mm 6 mm 5 mm 10 .times. 30
mm.sup.2 5 .times. 5 mm.sup.2 Energy density 30 J/cm.sup.2 25
J/cm.sup.2 40 J/cm.sup.2 25 J/cm.sup.2 3 J/cm.sup.2 30 J/cm.sup.2 6
J/cm.sup.2 Extended view parameters A min 8 mrad 3.5 mrad 4 mrad 4
mrad 2.5 mrad 5 mrad 15 mrad R max 0.4 m 2 m 2 m 2 m 1.3 m 4 m 0.33
m Eye safety Parameters AEL/sr 11 J/cm.sup.2/sr 4.3 J/cm.sup.2/sr
19.5 J/cm.sup.2/sr 20 J/cm.sup.2/sr 0.79 J/cm.sup.2/sr 3.4
J/cm.sup.2/sr 35 J/cm.sup.2/sr AR/sr 9.6 J/cm.sup.2/sr 8
J/cm.sup.2/sr 12.7 J/cm.sup.2/sr 8 J/cm.sup.2/sr 0.79 J/cm.sup.2/sr
9.5 J/cm.sup.2/sr 8 J/cm.sup.2/sr Eye safety 1.14 0.53 1.54 2.5 1
0.35 4.1 Figure of merit AEL/AR
The table shows that the exit beam according to the present
invention is essentially as eye-safe, or safer than, broad band
non-coherent intense pulsed light sources, such as those used for
professional photography or those used for cosmetic surgery. The
scattered monochromatic light, for most of the light sources, does
not necessitate protective eyeglasses and is safer than an
accidental glance into the sun for a fraction of a second. Although
the ratio for the Alexandrite and Intense Pulsed Light sources is
less than 1 and protective eyeglasses must be worn, the required
optical attenuation for these light sources is less than 3, much
less than the required optical attenuation with the use of a
conventional monochromatic light source not provided with a
diffusing unit, which is on the order of 10.sup.410.sup.7. It will
be appreciated that a similar level of eye safety for laser units
utilizing a diffusing unit may be achieved with a very wide
scattering angle, approaching a half angle of 60 degrees or a solid
angle of .PI. steradians. Small angle scattering may result in a
different level of eye safety when operated at an energy density
suitable for aesthetic treatments; nevertheless, such a scattered
exit beam is much safer than the exit beam of a conventional
coherent laser unit.
The radiance of the light emitted by a diffusing unit can be
measured to verify that it is in compliance with the appropriate
standards for laser eye safety. In one embodiment, a converted
laser utilizing a diffusing unit in accordance with the present
invention is provided with an eye safety measurement device. Such a
device may be an energy meter such as that produced by Ophir, USA
or an array of light detectors 805 as depicted in FIG. 16. The eye
safety measurement device is provided with control circuitry which
is in communication with the operating system of the laser unit, so
that, as a result of a mishap, a warning is issued indicating that
protective eyeglasses are required if the measured radiance of a
scattered laser beam is greater than a predetermined safe value.
Alternatively, the control circuitry may discontinue operation of
the laser unit if the measured radiance of a scattered laser beam
is greater than a predetermined safe value.
FIG. 16 illustrates an exemplary eye safety measurement device,
designated as numeral 800. Device 800 is operative to measure the
radiance of scattered light 810, which is scattered by means of
diffusing unit 15 attached to distal end 809 of laser unit
handpiece 801. Device 800 is provided with an array of light
detectors 806, e.g. complementary metal oxide semiconductor (CMOS)
detectors which provide light imaging, at distal end 805 thereof,
on which scattered light 810 impinges after passing through
aperture 808 of diameter Q.sub.0 and lens 807. After distal end 809
is inserted into a complementary opening formed within device 800
until contacting annular abutment plate 804 perpendicular to outer
wall 803 of device 800, the laser unit is fired. For purposes of
clarity, light which propagates through segment Q.sub.1 of
diffusing unit 15 impinges on segment Q.sub.2 of detector array
806. The radiance of scattered light 810 therefore is determined by
dividing the amount of energy sensed by detectors 806 by diameter
Q.sub.0 of aperture 808 and by the solid angle characteristic of
the detector structure. For example, the distance D between
abutment plate 804 and aperture 808 is 200 mm, segment Q.sub.i of
the diffusing element 15 is 0.7 mm, and diameter Q.sub.0 of the
aperture is 7 mm, to comply with the regulations set forth in ANSI
Z 136.1.
FIG. 17 illustrates another embodiment of the invention, wherein
eye safety in the vicinity of a laser unit that emits an infrared
beam or other invisible radiation is increased by adding a flashing
device to the laser system to cause one's eyes to blink during the
propagation of the laser beam.
FIG. 17a illustrates distal end 960 of a laser unit, which emits
light 955 generated therefrom, preferably being scattered
monochromatic light when a diffusing unit is employed. To prevent
damage to eye 962 of a bystander located in the vicinity of the
laser unit, flashing device 961 is added to distal end 960.
Flashing device 961 generates a short visible light flash a
fraction of a second prior to the firing of a laser beam.
As shown in FIG. 17b, activation of the laser unit initiates an
electrical pulse 963 at time to, which triggers a timer circuit
(not shown). The timing circuit is adapted to generate and transmit
pulse 964 at time t.sub.1 to flashing device 961, to produce a
flash is sensed by eye 962. Flashing device 961 may be a well known
flashing means associated with cameras or may utilize diodes, or
any other feasible means to produce an instantaneous flash. After a
predetermined period of time, the timing circuit transmits a pulse
to the control system of the laser unit to fire a laser beam at
time t.sub.2. This predetermined period of time, namely the
difference between t.sub.2 and t.sub.1, is approximately 0.25
seconds, equal to the reaction time of uncontrolled blinking as a
response to light, and is preferably no more than 0.20 seconds. A
flashing device 961 may be added to any source of monochromatic
light, such as any type of laser or IPL sources, whether producing
visible or invisible light.
FIG. 17c illustrates another application of flashing device 961. By
generating a flash with device 961 and determining whether detector
975 senses light retroreflected from eye 962, a microprocessor (not
shown) in communication with a control circuit (not shown) and with
detector 975, e.g. a photodetector, can determine that eye 962 is
in danger of being injured from the imminent firing of a laser beam
from the laser unit. The choroid layer of the retina diffusely
reflects light source 973 that impinges thereon from the previously
generated flash, and the optics of eye 962, re-image, or
retroreflect, the light back to flashing device 961. Retroreflected
beam 974 is reflected from beam splitter 970 through a lens (not
shown) onto 975. Two additional adjacent detectors (not shown)
detect light reflected from other areas in the room in which the
laser unit is disposed. If the signal generated by detector 975 has
a much larger amplitude than the signals generated by the
additional detectors, the microprocessor determines that eye 962 is
in firing range of a laser beam. The control circuit of flashing
device 961then sends a disabling signal to the control system of
the laser unit to thereby prevent firing of a laser unit. When
detector 975 is used to detect a retroflected beam, and a flash is
generated within the predetermined time before the firing of a
laser beam, as illustrated in FIG. 17b, in order to cause
uncontrollable blinking of the eye during propagation of the beam,
the laser unit is inherently fail-safe. That is to say, even if the
eye does not blink, detector 975 will determine that eye 962 is in
firing range of a laser beam and the laser unit will cease
operation.
As can be seen from the above description, a diffusing/diverging
unit of the present invention, which is mounted to the exit
aperture of a conventional laser unit, induces the exit beam to be
divergent/ and or scattered at a wide angle. As a result the exit
beam is not injurious to the eyes and skin of observers, as well as
to objects located in the vicinity of the target. Nevertheless, the
exit beam generally retains a similar level of energy density as
the beam generated from the exit aperture when the diffusing unit
is very close or essentially in contact with the target, and is
therefore capable of performing various types of treatment, both
for cosmetic surgery and for industrial applications. Protective
eyeglasses are generally not needed, and if they are needed,
conventional sunglasses would be the only requirement, thereby
allowing work in an aesthetic clinic to be less cumbersome.
In another embodiment of the invention, the apparatus is provided
with a unit for evacuating vapors, such as condensed vapors that
were produced during the chilling of skin prior to the firing of
the laser unit. The evacuation unit comprises a U-shaped vacuum
chamber through which monochromatic light passes as it is directed
to a skin target and a vacuum pump. During operation of the vacuum
pump, the vacuum level within the vacuum chamber is increased by
occluding a conduit of the vacuum chamber by a finger of the
operator. As vacuum is applied to the skin target, skin is drawn
toward the vacuum chamber and the concentration of blood vessels in
the vicinity of the target increases. The added concentration of
blood vessels increases the absorption of light within the tissue,
and therefore facilitates treatment of a skin disorder.
FIG. 18 illustrates the propagation of an intense pulsed laser beam
the wavelength of which is in the visible or near infrared region
of the spectrum, i.e. shorter than 1800 nm, from the distal end of
a handpiece to a skin target according to a prior art method.
Handpiece 1001 comprises clear transmitting element 1002, such as a
lens or a window, which transmits monochromatic beam 1007 emitted
from the laser unit and impinges skin target 1004. The beam
penetrates skin target 1004 and selectively impinges a subcutaneous
skin structure to be thermally injured, such as collagen bundle
1005, blood vessel 1009, or hair follicle 1006. In this method,
external pressure or vacuum is not applied to the skin.
FIG. 19 illustrates a prior art non-coherent intense pulsed light
system from which light is fired to a skin target for e.g.
treatment of vascular lesions, hair removal, or photorejuvenation.
Handpiece 1010 comprises light guide 1011 which is in contact with
skin target 1004. Beam 1012, which is generated by lamp 1013 and
reflected from reflector 1014, is non-coherent and further
reflected by the light guide walls. In some handpieces, such as
those produced by Deka (Italy), a clear transmitting element is
utilized, rather than a light guide. Chilling gel is often applied
to the skin when such a light system is employed. In this method,
external pressure or vacuum is not applied to the skin, and the
handpiece is gently placed on the skin target, so as to avoid
removal of the gel layer, the thickness of which is desired to
remain at approximately 0.5 mm.
FIG. 20 illustrates a prior art laser system similar to those of
U.S. Pat. Nos. 5,595,568 and 5,735,844, which employs an optical
component 1022 at the distal end thereof in contact with skin
target 1004. Pressure is applied to skin target 1004, in order to
expel blood from those portions of blood vessels 1025, as
schematically illustrated by the arrows, which are in the optical
path of subcutaneously scattered light, thereby allowing more
monochromatic light to impinge hair follicle 1006 or collagen
bundle 1005. Concerning hair removal, melanin is generally utilized
as an absorbing chromophore.
FIG. 21 illustrates a prior art device 1031, such as that produced
by LPG (France), which is in pressing contact with skin 1033 in
order to perform a deep massage of cellulite adipose layer 1037.
Device 1031 is formed with a convex surface 1039 in a central
region of its planar skin contacting surface 1043. Device 1031
stimulates the flow of lymphatic fluids in their natural flow
direction 1038 in order to remove toxic materials from the
adjoining tissue. The stimulation of lymphatic fluid flow is
achieved by applying a vacuum to the interior of device 1031 so
that air is sucked therefrom in the direction of arrow 1034 of the
skin. The application of the vacuum draws skin toward convex
surface 1039 and induces the temporary formation of skin fold 1040,
which is raised in respect to adjoining skin 1033. Due to the
elasticity of skin, skin fold 1040 returns to its original
configuration, similar to the adjoining skin, upon subsequent
movement of device 1031, while another skin fold is formed. As
device 1031 is moved by hand 1036 of a masseur in direction 1044 of
the device, similar to natural flow direction 1038 the lymphatic
fluids flow in their natural flow direction. However, the lymphatic
fluids will not flow if device 1031 were moved in a direction
opposite to direction 1044. Wheels 1035 enable constant movement of
device 1031.
In some cellulite massage devices, such as those produced by Deka
(Italy) or the Lumicell Touch (USA), a low power continuous working
infrared light source with a power level of 0.1-2 W/cm.sup.2
provides deep heating of the cellulite area and additional
stimulation of lymphatic flow. Such a light source is incapable of
varying the temperature by more than 2-3.degree. C., since higher
temperatures would be injurious to the tissue and cause
hyperthermia. Consequently these massage devices are unable to
attain the temperatures necessary for achieving selective thermal
injury of blood vessels, hair follicles or for the smoothening of
fine wrinkles. Due to the movement of the device, the amount of
optical energy, e.g. by means of an optical meter, to be applied to
the skin cannot be accurately determined.
FIG. 22 illustrates a prior art hair removal device, similar to the
device of U.S. Pat. No. 5,735,844, which is provided with a slot
1052 within a central region of skin contacting surface 1051 of
handpiece 1050. When handpiece 1050 is placed on skin surface 1058
and a vacuum is applied to the handpiece via opening 1053, skin
fold 1054 is formed. A narrow slot 1052 induces formation of a
correspondingly longer skin fold 1054. Optical radiation is
transmitted to the two opposed sides 1056 of skin fold 1054 by a
corresponding optical fiber 1055 and optical element 1057. Upon
application of the vacuum, skin fold 1054 is squeezed to prevent
blood flow therethrough. This device is therefore intended to
reduce the concentration of blood within skin fold 1054, in order
to increase illumination of melanin-rich hair shafts, in contrast
with the apparatus of this embodiment by which blood concentration
is increased within the slight vacuum-induced skin protrusion so as
to induce increased light absorption, as will be described
hereinafter. Furthermore, this prior art device, due to the reduced
concentration of blood within skin fold 1054, is not suitable for
treatment of vascular lesions, photorejuvination, or the method of
hair removal which is aided by the absorption of optical energy by
blood vessels that surround or underly hair follicles (as opposed
to the method of hair removal which is aided by the absorption of
optical energy by melanin.
FIG. 23 illustrates the apparatus according to an embodiment of the
invention, which is generally designated by numeral 1070. Apparatus
1070 comprises monochromatic light source 1071, handpiece 1073
provided with clear transmitting element 1076 at its distal end,
and an evacuation unit which is designated by numeral 1090.
Evacuation unit 1090 comprises vacuum pump 1080, vacuum chamber C,
and conduits 1078 and 1079 in communication with chamber C. Vacuum
chamber C, which is placed on skin surface 1075, is formed with an
aperture (not shown) on its distal end and is provided with a clear
transmitting element 1076 on its proximate end. Vacuum chamber C is
integrally formed with handpiece 1073, such that cylindrical wall
1091 is common to both handpiece 1074 and vacuum chamber C. Element
1076 is transparent to beam 1074 of intense pulsed light which is
directed to skin target T. Element 1076 is positioned such that
beam 1074 is transmitted in a direction substantially normal to
skin surface 1075 adjoining skin target T. The ratio of the maximum
length to maximum width of the opening, which may be square,
rectangular, circular, or any other desired shape, ranges from
approximately 1 to 4. Since the aperture is formed with such a
ratio, skin target T is proximately drawn, e.g. 1 mm from skin
surface 1075, and is slightly deformed, as indicated by numeral
1087, while increasing the concentration of blood in skin target T.
Likewise, employment of an aperture with such a ratio precludes
formation of a vacuum-induced skin fold, which has been achieved
heretofore in the prior art and which would reduce the
concentration of blood in skin target T.
Wall 1091 is formed with openings 1077 and 1084 in communication
with conduits 1078 and 1079, respectively. The two conduits have a
horizontal portion adjacent to the corresponding opening, a
vertical portion, and a long discharge portion. Openings 1077 and
1084 are sealed with a corresponding sealing element 1093, to
prevent seepage of fluid from the vacuum chamber. Conduit 1079 is
also in communication with vacuum pump 1080, which draws fluid,
e.g. air, thereto at subatmospheric pressures. U-shaped vacuum
chamber C is therefore defined by clear transmitting element 1076
of the handpiece, slightly deformed skin surface 1087, wall 1091
and conduits 1078 and 1079.
A suitable light source is a pulsed dye laser unit, e.g. produced
by Candela or Cynosure, for the treatment of vascular lesions,
which emits light having a wavelength of approximately 585 nm, a
pulse duration of approximately 0.5 microseconds and an energy
density level of 10 J/cm.sup.2. Similarly any other suitable high
intensity pulsed laser unit, such as a Nd:YAG, pulsed diode,
Alexandrite, Ruby or frequency doubled laser, operating in the
visible or near infrared region of the spectrum may be employed.
Similarly, a laser unit generating trains of pulses, such as the
Cynosure Alexandrite laser, the Lumenis "Quatim" IPL or Deka
"Silkapill". The emitted light is transmitted via optical fiber
1072 to handpiece 1073. Handpiece 1073 is positioned such that
clear transmitting element 1076 faces skin surface 1087. Beam 1074
propagating towards slightly protruded skin surface 1087 is
substantially normal to skin surface 1075.
Following operation of vacuum pump 1080, air begins to become
evacuated from vacuum chamber C via conduit 1079. Occluding conduit
1078, such as by placing finger 1083 of an operator on its outer
opening increases the level of the vacuum within chamber C to a
pressure ranging from 200 to 1000 millibar. The application of such
a vacuum slightly draws skin target T towards chamber C without
being pressed, as has been practiced heretofore in the prior art,
thereby increased the concentration of blood vessels within skin
target T. The efficacy of a laser unit in terms of treatment of
vascular lesions is generally greater than that of the prior art,
due to the larger concentration of blood vessels in skin target T,
resulting in greater absorption of the optical energy of beam 1074
within bodily tissue.
The operator may fire the laser following application of the vacuum
and the subsequent change in color of skin target T to a reddish
hue, which indicates that the skin is rich in blood vessels. The
time delay between the application of the vacuum and the firing, of
the laser is based on clinical experience or on visual inspection
of the tissue color.
FIG. 24 illustrates another embodiment of the present invention
wherein the operation of the vacuum pump and the pulsed laser unit
are electronically controlled. The depth of light penetration
within the tissue may be controlled by controlling the time delay
between application of the vacuum and the firing of the pulsed
laser. If the time delay is relatively short, e.g. 10 msec, blood
vessel enrichment will occur only close to the surface of the skin
at a depth of approximately 0.2 mm, while if the delay is
approximately 300 msec, the blood vessel enrichment depth may be as
great as 0.5-1.0 mm.
Apparatus 1170 comprises handpiece 1101, laser system 1116,
evacuation unit 1190 and control unit 1119.
Laser system 1116 includes a power supply (not shown), a light
generation unit (not shown), and power or energy detector 1130 for
verifying that the predetermined energy density value is applied to
the skin target. Handpiece 1101 held by the hand of the operator is
provided with lens 1104, which directs monochromatic beam 1105
transmitted by optical fiber 1103 from laser system 1116 to skin
target area 1140. Clear transmitting element 1100 defining vacuum
chamber 1106 is generally in close proximity to skin surface 1142,
at a typical separation H of 1.2 mm and ranging from 0.5 to 4 mm,
depending on the diameter of the handpiece. The separation is
sufficiently large to allow for the generation of a vacuum within
chamber 1106, but less than approximately one-half the diameter of
the window 1100, in order to limit the protrusion of skin target
1140 from the adjoining skin surface 1142. By limiting the
separation of element 1100 from skin surface 1142 while maintaining
the vacuum applied to skin target 1140, formation of a skin fold is
precluded while more blood may be accumulated in a smaller skin
thickness. Therefore a significant local rise in the temperature of
a blood vessel, which ranges from 50.70.degree. C., is made
possible.
Evacuation unit 1190 comprises vacuum chamber 1106 which is not
U-shaped, miniature vacuum pump 1109 suitable for producing a
vacuum ranging from 200-1000 millibar, conduit 1107 and control
valve 1111 through which subatmospheric fluid is discharged from
chamber 1106, and miniature pressurized tank 1110 containing, e.g
100 ml, which delivers air through conduit 1112 and control valve
1108 to chamber 1106. If so desired, a clear transmitting element
need not be used, and vacuum chamber 1106 defined by lens 1104 will
have an accordingly larger volume.
Control unit 1119 comprises the following essential elements:
a) Display 1115 of the energy density level of the monochromatic
light emitted by laser system 1116 and a selector for selecting a
predetermined energy density.
b) Confirmation indicator 1120 which verifies that the selected
energy density is being applied to the skin. Control circuitry
deactivates the laser power supply if a beam having an energy
density significantly larger than the predetermined value is being
fired. c) Display 1122 concerning the pulse structure, such as
wavelength, pulse duration and number of pulses in a train. d)
Control circuitry 1123 for selecting the time delay between
operation of vacuum pump 1109 and laser system 1116. e) Selector
1124 for controlling the vacuum level in vacuum chamber 106 by
means of pump 1109. f) Control circuitry 1126 for controlling the
vacuum duty cycle by regulating the operating cycle of vacuum pump
1109, the open and close time of control valve 1111, the average
vacuum pressure, the vacuum modulation frequency, and the
repetition rate. g) Control circuitry 1143 for delivering fluid
from positive pressure tank 1110 by controlling the duty cycle of
control valve 1108.
Tank 1110, in which air having a pressure ranging from 1.2
atmospheres is contained, provides a fast delivery of less than 1
msec of air into chamber 1106, as well as a correspondingly fast
regulation of the vacuum level therein by first opening control
valves 1108 and 1111 and activating vacuum pump 1109. After a
sufficient volume of fluid, e.g 1 ml, is delivered to chamber 1106,
control valve 1108 is closed. Control circuitry 1126 and 1143 then
regulate the operation of the control valves so to maintain a
predetermined level of vacuum. Upon achieving the predetermined
vacuum level, control circuitry 1123 fires laser system 1116 after
the predetermined time delay, which may range from 1-1000 msec.
FIG. 25 illustrates apparatus 1270, which comprises a non-coherent
intense pulsed light system similar to that described with respect
to FIG. 19 and provided with Xe flashlamp 1201, such as one
manufactured by Lumenis, Deka, Palomar, or Syneron. Reflector 1202
reflects the emitted light 1207 to light guide 1208. Distal end
1203 of light guide 1208 is separated 1-2 mm from skin surface 1242
to allow for the generation of a vacuum in vacuum chamber 1206
without compromising treatment efficacy by limiting the protrusion
of the skin target from the adjoining skin surface 1242.
FIG. 26 illustrates the placement of apparatus 1370 onto arm 1310.
Apparatus 1370 comprises handpiece 1301, evacuation unit 1390, and
skin chiller 1300 for cooling the epidermis of arm 1310, which is
heated as a result of the impingement of monochromastic light
thereon. Skin chiller 1300 is preferably a metallic plate made of
aluminum, which is in contact with the epidermis and cooled by a
thermoelectric cooler. The temperature of the plate is maintained
at a controlled temperature, e.g. 0.degree. C. The chilled plate is
placed on a skin region adjacent to skin target 1340. The epidermis
may be chilled prior to the light treatment by other suitable
means, such as by the application of a gel or a low temperature
liquid or gas sprayed onto the skin target.
It will be appreciated that the utilization of a U-shaped vacuum
chamber 1306 for the evacuation of vapors which condense on clear
transmitting element 1376 is particularly advantageous when a skin
chiller in permanent contact with the handpiece outer wall is
employed. Such a skin chiller is illustrated in FIG. 26 or FIG.
15f, resulting in condensation of vapors on the transmitting
element that would not be evacuated without employment of an
evacuation unit in accordance with the present invention. When the
skin chiller of FIG. 15f is employed, the skin chiller is
displaced, for example by a releasable attachment means as shown in
FIG. 2e or by any other suitable method, such that it is contact
with the vacuum chamber.
FIG. 27 schematically illustrates the effect of applying a
subatmospheric pressure to a skin target, in accordance with the
present invention, in order to enhance the absorption of light by
blood vessels within the skin target. For clarity, the drawing
illustrates the effect with respect to a single blood vessel;
however, it should be appreciated that many blood vessels
contribute to the effect of increased blood transport whereby a
plurality of blood vessels are drawn to the epidermis, resulting in
increased absorption of the optical energy. The protrusion of the
skin target relative to the adjoining skin surface is also shown in
disproportionate fashion for illustrative purposes.
The increase in light absorption within blood vessels due to the
application of a vacuum in the vicinity of a skin target depends on
the vacuum level, or the rate of vacuum modulation, and the skin
elasticity which is reduced with increased age. As shown, blood
vessel 1329 of diameter D is in an underlying position relative to
vacuum chamber 1326. By applying a vacuum by means of evacuation
unit 1390, blood flow is established in blood vessel 1329 in the
direction of arrow M, due to a difference of pressures between
points A and B closer and farther from vacuum chamber 1326,
respectively. If the blood vessel is a vein, the flow will be
established in only one direction, due to the influence of the
corresponding vein valve.
According to the Hagen-Poisseuille equation concerning the flow of
viscous fluids in tubes, the discharge from a tube and consequently
the duration of flow therethrough depends on a pressure gradient
along the tube, the fourth power of the diameter of the tube, and
the length thereof. For example, diameters of 100 microns are
common for capillaries adjacent to the papillary dermis at a depth
of approximately 200 microns and 500 micron blood vessel diameters
can be found in the hair bulb at a depth of 3 mm. A typical blood
vessel length is approximately 1-2 cm. It will be appreciated that
although the blood vessel diameters generally increase with depth,
the pressure gradient along the blood vessel is smaller at deeper
layers of the skin. As a result, for a given pressure, such as the
application of a zero millibar vacuum, each depth from the skin
surface corresponds to a characteristic time response for being
filled by blood. As a result, modulation of the vacuum by opening
and closing control valve 1111 (FIG. 24) controls the flow of blood
through blood vessels and consequently controls the degree of light
absorption by a blood vessel at a given depth from skin surface
1342. In a realistic situation wherein a plurality of blood vessels
are located within a skin target, each skin layer is characterized
by a different modulation frequency which typically ranges between
100 Hz for upper layers and 1 Hz for the deep layers under the hair
follicles. By opening control valves 1108 and 1111 (FIG. 24) by a
varying frequency, the operator may modulate the vacuum applied to
the skin target and thereby vary the blood richness of different
skin layers.
The operator typically determines an instantaneous modulation
frequency of control valves 1108 and 1111 by visually inspecting
the skin target and viewing the degree of redness thereat in
response to a previous control valve modulation frequency. In
addition to improving the treatment efficacy, an increased degree
of redness within the skin target advantageously requires a lower
energy density of intense pulsed light for achieving blood
coagulation or blood heating resulting in the heating of the
surrounding collagen. Alternatively, an errythema, i.e. skin
redness, meter, e.g. produced by Courage-Hazaka, Germany, may be
employed for determining the degree of redness, in order to
establish the necessary energy density for the treatment.
For example, a modulation frequency as high as 40 Hz or the firing
of a Dye laser unit approximately 1/40 seconds after application of
a, vacuum may be necessary for applications of port wine stains. In
contrast, a delay of approximately a half second for fine wrinkle
removal and of approximately 1 second for hair removal may be
needed for a depth of 1-3 mm under the skin surface.
FIG. 28 illustrates the concentration of a plurality of blood
vessels 1329 in a skin target 1340, which results in the increase
of redness of skin and enhanced absorption of light with respect to
the hemoglobin absorption spectrum and scattering properties of
skin. Light absorption is enhanced by a larger number of blood
vessels per unit volume due to the correspondingly larger number of
light absorbing chromophores. The beneficial effect of vacuum
assisted absorption by Dye lasers or any yellow light, which is
strongly absorbed by hemoglobin, is more pronounced on white or
yellow skin not rich in blood vessels, such as that of smokers.
Such types of skin suffer from enhanced aging and require
photorejuvenation, the efficacy of which is improved with the use
of the present invention. Enhanced absorption of light is also
advantageously achieved when infrared lasers and intense pulsed
light sources are employed.
FIG. 29 is a photograph illustrating the treatment of a fine
wrinkle 1401 by means of a vacuum assisted handpiece according to
the current invention, which was taken one-half of a second after
the application of a vacuum. Circles 1402-4 indicate the sequential
treatment spots. The color in the circle 1403 has changed.
FIG. 30 illustrates apparatus 1570 which increases blood vessel
concentration within a skin target without use of a handpiece.
Apparatus 1570 comprises evacuation unit 1590 having a transparent
vacuum chamber 1501 made of a thin, transparent polymer 1506, such
as polycarbonate or glass, which is transparent to visible or near
infrared light. Vacuum chamber 1501 has a diameter of 5.20 mm and a
height of approximately 1.3 mm, in order to avoid excessive
protrusion of the skin. Chamber 1501 is preferably cylindrical,
although other configurations are also suitable. Soft silicon rim
502 is adhesively affixed to the periphery of the chamber 1501, in
order to provide good contact with skin surface 1542. Conduit 1503
in communication with control valve 1504 allows for the evacuation
of vacuum chamber 1501 by means of a miniature vacuum pump (not
shown) and control unit 1505. After chamber 1501 is placed on skin
target 1540, pulsed beam 1508 from any existing intense pulsed
laser or light source 1509 which operate in the visible or near
infrared regions of the spectrum may propagate therethrough and
effect treatment of a skin disorder. The advantage of this
apparatus is its low price and its ability to interact with any
intense pulsed laser or non-coherent light source which is already
installed in a health clinic.
The absorption of visible intense pulsed light in blood vessels
when vacuum is applied to a skin target may be enhanced by the
directing electromagnetic waves to the skin target. Radio frequency
waves operating in the range of 0.2-10 Mhz are commonly used to
coagulate tiny blood vessels. The alternating electrical field
generated by a bipolar RF generator, such as produced by Elman,
USA, follows the path of least electrical resistance, which
corresponds to the direction of blood flow within blood
vessels.
FIG. 31 illustrates apparatus 1870 which comprises intense pulsed
laser or intense pulsed light source 1821, RF source 1811, and
evacuation unit 1890. Evacuation unit 1890 comprises vacuum chamber
1801, which is placed on skin surface 1802 to be treated for
vascular lesions, miniature vacuum pump 1805, and control valve
1804 for regulating the level of the vacuum in chamber 1801. Clear
transmitting element 1806 is positioned in such a way that beam
1820 generated by light source 1821 propagates therethrough and
impinges skin surface 1802 at an angle which is substantially
normal to the skin surface.
RF source 1811 is a bipolar RF generator which generates
alternating voltage 1807 applied to skin surface 1802 via wires
1808 and electrodes 1809. Electric field 1810 generally follows the
shape of blood vessels 1813, which are the best electrical
conductors in the skin. Due to the concentration of blood vessels
1813 in the epidermis, the depth of which below skin surface 1802
depending on the vacuum level and the frequency of vacuum
modulation, the combined effect of optical energy in terms of beam
1820 and pulsed RF field 1810 heats or coagulates the blood
vessels.
Control valve 1804 is regulated by means of control unit 1812. A
first command pulse 1 of control unit 1812 controls valve 1804 and
a second command pulse 2 controls a delayed radio frequency pulse
as well as a delayed light source pulse.
Example 1
An experiment was performed to demonstrate the operating principles
of the present invention in which transparent light diffusing
adhesive "Magic Tape," manufactured by 3M, having a thickness of
100 microns was attached to the distal end of an Alexandrite laser
unit having a diameter of 8 mm. The energy level of the laser beam
is 11 J/pulse. The laser beam was directed to the white (rear) side
of a black developed photographic paper having a thickness of 300
microns. For comparison, the laser beam was also directed to the
photographic paper without the use of the adhesive tape.
The ablation of the black paper after the beam had propagated and
scattered through the white paper provides a visual simulation of
the capability of the laser beam to penetrate transparent
light-scattering skin in order to treat black hair follicles (or
any other type of lesion) under the skin.
The energy of the laser beam transmitted through the adhesive tape,
which caused the laser beam to scatter, was measured by directing
the beam to an energy meter located at a distance of 1 mm from the
distal end of the laser unit. The energy of the scattered laser
beam dropped from 11 to 10 J. The results of this experiment
indicate that the diffusively transmitting element did not absorb a
significant amount of energy, since a loss of 10% is expected in
any case due to Fresnel reflection.
When the laser beam was directed to the white (rear) side of a
developed photographic plate at a distance of 1 mm, an ablation of
the black color on the opposite side of the photographic paper
resulted. There was no difference in the results between usage of
light diffusing tape or not. This experiment demonstrates that the
performance of a non-coherent Alexandrite laser beam, according to
the present invention, at a distance of 1 mm is essentially equal
to the corresponding coherent laser beam.
When the laser beam was directed, without the addition of light
diffusing tape, at the photographic paper from a distance of at
least 8 mm, an ablation resulted that is identical to that which
was generated from a short distance of 1 mm. However, when light
diffusing tape was applied to the exit aperture of the laser unit
from a distance of at least 8 mm, the scattered beam did not result
in an ablation. Accordingly, the present invention allows for a
high level of safety and lack of damage to bodily tissue when
disposed at a relatively large distance therefrom.
Example 2
In a second experiment a long pulse Alexandrite laser unit having a
wavelength of 755 nm, pulse duration of 90 msec, and having an
energy density of 25 J/cm.sup.2 was used for hair removal. A
diffusing unit with an ultra-densely woven polymer-based diffuser
having a half angle of 15 degree produced by Barkan or a
holographic diffuser produced by Physical Optics Corporation (USA)
having a half angle of 40 degrees was employed. The diffusers were
used in a one-time basis. Chilling gel was applied between the
diffuser and the skin.
Each pulse of a laser beam scattered by a diffusing unit formed a
spot of 5.5 mm on-various skin locations including arms, bikini
lines and armpits of 10 patients. Full hair removal was noticeable
immediately after the firing of the laser beam. Each spot was
compared to a control area with an identical diameter formed by an
unscattered laser beam generated by the same laser unit with
similar parameters, and similar results were achieved. Hair did not
return to those spots for a period of one month.
Example 3
A long pulse Alexandrite laser unit having a wavelength of 755 nm,
pulse duration of 40 msec, and having an energy level of 1.20 J is
suitable for hair removal.
The diameter of the diffusing unit is 7 mm, and its scattering half
angle is 60 degrees. A diffusing unit comprising a diffuser with a
small scattering angle, a highly divergent lens and a light guide
is added to the distal end of the laser unit.
The prior art energy density of 10.50 J/cm.sup.2 is not
significantly reduced with the employment of a diffusing unit. The
laser unit operates at 25 J/cm.sup.2 and generates a radiance of 8
J/cm.sup.2/sr. Since the acceptable radiance limit according to
ANSI Z 136.1 is 4.3 J/cm.sup.2/sr, bystanders are required to use
protective eyeglasses with 50% optical attenuation, an attenuation
similar to that of sunglasses and an order of 100,000 less than
typical protective eyeglasses worn during operation of a laser
unit. For a larger target area, a scanner such as the Epitouch
model manufactured by Lumenis may be used.
A diffusing unit having a diameter of up to 7 mm is particularly
suitable for lower energy lasers, which are relatively small,
remove hair at a slower speed from limited area and are
inexpensive. An application of such a laser, when employed with a
diffusing unit, includes the removal of eyebrows.
Example 4
A pulsed Nd:YAG laser unit such as one produced by Altus (USA) or
Deka (Italy) having a wavelength of 1064 nm, pulse duration of 100
msec, and having an energy level of 0.5-60 J is suitable for hair
removal at an energy density ranging from 35-60 J/cm.sup.2.
A diverging unit with an array of focusing lenslets, an array of
lenses provided with reflective coating on its distal side, and a
plurality of convex reflectors attached to a transparent plate is
used, such that the diverging half angle is close to 60 degrees.
When a laser beam having an energy density of 40 J/cm.sup.2 is
generated, a radiance of 12.7 J/cm.sup.2/sr at the exit of the
diverging unit is induced, approximately half of the maximal
permitted radiance according to ANSI Z 136.1.
Example 5
A long pulse diode laser unit having a wavelength ranging from
810-830 nm, or of 9.10 nm or 940 nm pulse duration ranging from
1.200 msec, and having an energy level of 0.5-30 J is suitable for
hair removal at an energy density ranging from 20-50
J/cm.sup.2.
The diameter of the treated area, or spot size, ranges from 1.20
mm. The diffusively transmitting element is preferably made from
fused silica, sapphire, or is a holographic diffuser used in
conjunction with a light guide or with any other diffusing unit
described hereinabove. The scattering half angle is close to 60
degrees. A scanner may be integrated with the diffusing unit. The
delivery system to which the diffusing unit is attached may be a
conical light guide, such as that manufactured by Coherent or
Lumenis, a guide tube produced e.g. by Diomed or a scanner produced
e.g. by Assa. With a diffusing unit having a diameter of 5 mm and a
laser beam generated with an energy density of 20 J/cm.sup.2 and a
pulse duration of 100 msec, the radiance at the exit of the
diffusing unit is 9.6 J/cm.sup.2/sr, lower than the maximal
permitted radiance value of 11.0 J/cm.sup.2/sr.
Example 6
A miniature diode laser unit for home use operating at a wavelength
of approximately 810 nm, or 940 nm, such as one produced by
Dornier, Germany, and having a power level of 4 W is suitable for
hair removal. The invention converts a continuous working diode
laser unit, which is in a high safety class and usually limits
operation to the medical staff, into a lower safety class, similar
to non-coherent lamps of the same power level.
The diffusing unit utilizes an angular beam expander with a convex
reflector, a concave reflector having an inner diameter of 16 mm, a
10-degree glass diffuser, and a light guide having a length of 20
mm and an inner diameter of 2 mm. The diameter of the treated area,
or spot size, is approximately 2 mm. The energy density at the exit
of the light guide is 30 J/cm.sup.2 and the radiance thereat is
approximately 10 J/cm.sup.2/sr. A scanner may be integrated with
the diffusing unit. The diode laser may also be used without a
scanner, in which case the laser will be pulsed for a duration of
approximately 300 msec.
Example 7
A Ruby laser unit having a wavelength of 694 nm, pulse duration
ranging from 0.5-30 msec, and having an energy level of 0.2-20 J is
suitable for hair removal.
The diameter of the treated area, or spot size, ranges from 1-20
mm. The larger spot sizes can be generated by Ruby lasers
manufactured by Palomar, ESC and Carl Basel, which provide an
energy density ranging from 10-50 J/cm.sup.2. The smaller spot
sizes can be generated by inexpensive low energy lasers, which are
suitable for non-medical personnel. A multi-component diffusing or
diverging unit may be used. The laser unit is much safer than a
conventional laser unit
A scanner, such as manufactured by Assa of Denmark or by ESC, may
be used to displace a reflected collimated beam from one aperture
to another formed within the diffusing or diverging unit. The
scanning rate is variable, and the dwelling time at each location
ranges from 20-300 msec.
Example 8
High risk laser units, such as Nd:YAG having a wavelength of 1.32
microns and manufactured by Cooltouch with a pulse duration of up
to 40 msec, a dye laser having a wavelength of 585 nm and
manufactured by N-Light/SLS/ICN, or a Nd:Glass laser having a
wavelength of 1.55 microns with a pulse duration of 30 millisec may
be used for non-ablative skin rejuvenation. This application is
aimed at the treatment of rosacea, mild pigmented lesions,
reduction of pore sizes in facial skin and mild improvement of fine
wrinkles, without affecting the epidermis. The advantage of these
lasers for non-ablative skin rejuvenation is related to the short
learning curve and more predicted results due to the small number
of treatment parameters associated with the single wavelength. By
implementing a diffusing unit, the laser unit becomes safe and may
be operated by non-medical personnel.
An N-Light laser unit is initially operated at an energy density of
2.5 J/cm.sup.2 for collagen contraction. The addition of a
diffusing unit makes the laser unit as safe as an IPL. The addition
of a multi-component diffusing or diverging unit with a divergent
half angle of 60 degrees and an exit diameter of 5 mm results in a
radiance level of 0.79 J/cm.sup.2/sr, which is equal to maximal
accepted limit.
A laser beam may be generated with a considerably less expensive
laser unit, having an energy level ranging from 0.5-3 J and a slow
repetition rate such as 1 pps, and generating a spot size ranging
from 2-4 mm. In the case of wrinkle removal, the operator may
follow the shape of the wrinkles with a small beam size. Such a
non-coherent laser beam having a beam size of 2-4 mm is
particularly suitable for aestheticians. Using a diffusing unit
depicted in FIG. 10b with a 10 degree diffuser and a light guide
having a length of 30 mm results in a laser unit with a radiance of
approximately 0.5 J/cm.sup.2/sr.
Example 9
A pulsed Nd:YAG laser unit having a wavelength of 1064 nm and
manufactured by ESC and having an energy level of 0.5-60 J is
suitable for treatment of vascular lesions. The pulse duration
ranges from 1.200 msec, depending on the size of the vessels to be
coagulated (300 microns to 2 mm) and the depth thereof below the
surface of the skin. A LICAF (Litium Calcium Fluoride) laser unit
at a wavelength of 940 nm may also be advantageously used for this
application, and its associated laser beam is better absorbed by
blood than the Nd:YAG or Dye laser. A Dye laser at a wavelength of
585 nm and manufactured by Candela may be used to treat vessels
located at a low depth below the skin surface, such as those
observed in port wine stain, telangectasia and spider veins.
The diameter of the treated area, or spot size, ranges from 1-10
mm, depending on the energy level. A multi-component diffusing or
diverging unit is used, due to the relatively high energy density
of greater than 90 J/cm.sup.2 needed for the treatment of deep
vascular lesions. A scanner may be integrated with the diffusing
unit.
Example 10
Q-Switch laser units having a pulse duration ranging from 10-100
nsec and having an energy density of 0.2-10 J/cm.sup.2 is suitable
for removal of pigmented spots, mostly on the face and hands, as
well as removal of a tattoos. A Q-switched Ruby laser as
manufactured by ESC or Spectrum, a Q-Switch Alexandrite laser
manufactured by Combio, and a Q-Switch Nd:YAG laser may be used for
such an application.
The diameter of the treated area, or spot size, ranges from 1-10
mm, depending on the energy level. A diffusing unit utilizing two
diffusively transmitting elements is used, wherein one is fixed
while the other is axially displaceable such that both elements are
essentially in contact with each other in an active position, e.g.
a gap of approximately 0.2 mm when a laser beam is fired. The gap
between the two elements is approximately 15 cm when the laser is
not fired. The diameter of the diffusing unit is 6 mm. Each
diffusively transmitting element is preferably made from glass,
sapphire or polymer.
The addition of such a diffusing unit with an axially displaceable
diffuser to the aforementioned laser units is instrumental in
rendering pigmented lesion and tattoo removal to be a considerably
less risky procedure. Tattoo removal is achieved only by means of a
laser beam, and is not attainable with intense pulse light
sources.
The removal of pigmented lesions may also be performed with the use
of an Erbium laser unit operated at a wavelength of 3 microns. Most
pigmentation originates from the epidermis, and such a laser beam
penetrates only a few microns into the skin. With implementation of
a diffusing unit, this procedure may not necessarily be performed
by medical specialists. Aestheticians will be able to treat a large
number of patients, particularly since an Erbium laser is
relatively inexpensive.
Another application of the present invention involves the field of
dentistry, and relates to the treatment of pigmented lesions found
on the gums. Q-switched as well as Erbium lasers may be used for
this application.
Example 11
A CO.sub.2 laser may be used for wrinkle removal. In prior art
devices, such a laser is used in two ways in order to remove
wrinkles: by ablation of a thin layer of tissue at an energy
density greater than 5 J/cm.sup.2 with a Coherent Ultrapulse, ESC
Silktouch, or Nidek Coe laser and scanner for a duration less than
1 msec; or by non-ablative heating of collagen in the skin for
lower energy densities, such as at 3 W, which may be achieved by
operation of a continuously working ESC derma-K laser for 50 msec
on a spot having a diameter of 3 mm.
With implementation of the present invention in which a
multi-component diffusing or diverging unit is attached to a
CO.sub.2 laser, a laser beam having a wavelength of 10.6 microns
may be generated. As opposed to other far infrared sources whose
thermal and spectrally broad bandwidth involves less control of
penetration depth, the interaction of a laser beam with tissue
according to the present invention is highly controllable and its
duration can be very short.
The diffusing and diverging units are preferably made from a
lenslet that is transparent to a CO.sub.2 laser beam such as ZnSe
or NaCL. The diameter of the diffusing unit ranges from 1.10 mm.
The divergent angle is greater than the minimal acceptable value so
as to produce a radiance level at the exit beam that is essentially
eye safe.
During ablation, a clear transmitting element of the diffusing unit
is separated from the tissue to be treated by a thin spacer having
a thickness of approximately 1 mm to allow for the evacuation of
vapors or smoke produced during the vaporization process.
Similarly an Erbium laser unit operating at an energy density above
2 J/cm.sup.2 and generating a laser beam greater than 3 microns may
be used for wrinkle removal. Ablation is shallower than attained
with a CO.sub.2 laser and application of an Erbium laser unit can
be extended to tattoo or permanent make up removal.
Example 12
A Nd:YAG or other laser unit may be used for treatment of herpes. A
diode laser with selective absorption of Cyanin green or other
materials by fatty lesions may be used for treatment of acne. Both
of these lasers may be used for treatment of hemorroids and for
podiatric lesions on the feet.
Example 13
A dye laser unit operating at a wavelength of approximately 630 nm
or 585 nm, or at other wavelengths which are absorbed by natural
porpherins present in P acne bacterias, such as produced by
Cynachore or SLS, as well as a laser unit operating at 1.45 microns
as produced by Candella, may treat acne lesions. The addition of a
diffusing or diverging unit to the laser unit may considerably
enhance eye safety and simplify the use of the laser unit for such
treatments by nurses and non-medical staff.
Example 14
CO.sub.2, diode and Nd:YAG laser units operating at an average
power of approximately 1-10 W are currently used by physicians to
treat pain. The addition of a diffusing unit may enable the use of
a highly safe device for that procedure in pain clinics by
non-medical personnel. Each laser unit may generate a number of
repetitively occurring sets of pulses, during a period of
approximately 3 seconds. The delivery system of the laser beam may
be an articulated arm or an optical fiber.
Example 15
A diode laser unit manufactured by Candella (USA) generating a
laser beam with an energy density of 10 J/cm.sup.2, a wavelength of
1445 nm, a pulse duration of 100 msec and a spot size of 3 mm is
suitable for non-ablative photorejuvenation.
A diverging unit with a single converging lens focuses the beam to
a focal zone 1.5 mm proximate to the distal end of the diverging
unit and produces a half angle divergence of 45 degrees. The
diverging unit is provided with a shield located 10 mm distal to
the focal point, whereat the energy density is reduced to an eye
safe level of 0.2 J/cm.sup.2 and a spot size is 23 mm.
Example 16
It is advantageous to use an eye-safe laser unit for welding. The
employment of a diffusing unit is an excellent way to reduce the
risks associated with laser welding.
When welding thin transparent parts, such as those made from
plastic, e.g with a diode laser unit, it is often advantageous to
employ a large surface scanner or a large diameter beam which will
irradiate a large surface area and selectively activate all targets
with appropriate chromophores (by heat). Such a scanner is in
contrast to a scanner which is specifically targeted to the
geometrical locations at which welding materials are present. The
dwelling time of the welding laser beam at the targets depends on
the size of the welding element and the depth of material to be
melted. The dwelling time is also dependent on the size of a target
treated in photothermolysis. As an example, welding a strip having
a thickness of 50 micron to a substrate necessitates a dwelling
time of approximately 1 msec, while a strip having a thickness of
200 microns requires a dwelling time of 16 msec. The dwelling time
is proportional to the square of the thickness. Some welding
chromophores are transparent in the visible part of the spectrum,
but exhibit strong absorption in the near infrared part of the
spectrum.
Example 17
Another industrial application for the present invention is
associated with microstructures to be evaporated. Paint stains or
ink may be selectively evaporated from surfaces such as clothes,
paper and other materials that need cleaning by use of various
pulsed lasers. One example of this application is related to the
restoration of valued antiques. Another example is the selective
vaporization of metallic conductors which are coated on materials
such as glass, ceramics or plastics. Vaporization of metallic
conductors can be achieved with a pulsed laser, which is generally
separated by a short distance from a target and whose beam has a
duration ranging from 10 nanoseconds to 10 milliseconds. Pulsed
Nd:YAG lasers are the most commonly used ablative industrial
lasers, although other lasers are in use as well. Pulsed Nd:YAG
industrial lasers may attain an energy level of 20 J concentrated
on a spot of 1 mm, equivalent to an energy density of 2000
J/cm.sup.2. The addition of a diffusing unit to an industrial laser
considerably increases the safety of the ablative device.
Pulsed Nd:YAG laser units are also suitable for improving the
external appearance of larger structures, such as the cleaning of
buildings, stones, antique sculptures and pottery. The laser units
in use today are extremely powerful, having a continuously working
power level of up to 1 kW, and are therefore extremely risky. The
addition of a diffusing unit considerably improves the safety of
these laser units.
A diffusing unit, when attached to an Excimer laser unit, is
suitable for photo-lithography, or for other applications which use
an Excimer laser unit for a short target distance.
With the addition of a multi-component diffusing or diverging unit,
all of these applications become much safer to a user.
Example 18
An experiment was performed to determine the time response of skin
erythema following application of a vacuum onto various skin
locations. A pipe of 6 mm diameter was sequentially placed on a
hand, eye periphery, arm, and forehead at a subatmospheric pressure
of approximately 100 millibar. The skin locations were selected
based on the suitability for treatment: the hands and eye periphery
for wrinkle removal, arm for hair removal, and forehead for port
wine stain treatment. The vacuum was applied for the different
periods of time of 1/10, 1/4, 1, 2, 3 seconds and then stopped. The
erythema level and erythema delay time were then measured.
The response time of the hand and eye periphery was 1/2 sec, the
response time of the arm was 1 second and the response time of the
forehead was 1/2 second. Accordingly, the experimental results
indicate that the necessary delay between the application of the
vacuum and firing of the laser or intensed pulsed light is
preferably less than 1 second, so as not to delay the total
treatment time, since the repetition rate of most laser or intensed
pulsed light sources is generally less than 1 pulse/sec.
The erythema delay time was less than 1 second, and therefore the
experimental results indicate that patients will not sense
appreciable aesthetic discomfort following treatment in accordance
with the present invention.
Example 19
An intense pulsed light system comprising a broad band Xe flashlamp
and a cutoff filter for limiting light transmission between 755 nm
and 1200 nm is suitable for aesthetic treatments, such that light
delivered through a rectangular light guide is emitted at an energy
density of 20 J/cm.sup.2 and a pulse duration of 40 milliseconds,
for hair removal with respect to a treated area of 15.times.45
mm.
While efficacy of such a light system for the smoothening of fine
wrinkles, i.e. photorejuvenation, is very limited by prior art
devices, due to the poor absorption of light by blood vessels at
those wavelengths, enhanced light absorption in targeted skin
structures in accordance with the present invention would increase
the efficacy.
A transparent vacuum chamber of 1 mm height is preferably
integrally formed with a handpiece through which intense pulsed
light is directed. A diaphragm miniature pump, such as one produced
by Richly Tomas which applies a vacuum level of 100 millibar, is in
communication with the chamber and a control valve is
electronically opened or closed. When the control valve is opened,
the pressure in the vacuum chamber is reduced to 100 millibar
within less than 10 milliseconds. As a result of the application of
vacuum, the skin slightly protrudes into the vacuum chamber at an
angle as small as 1/15- 1/45 radian (height divided by size of skin
target) and a height of 1 mm. Blood is drawn into the drawn skin
target, which achieves a much pinker hue and therefore has a higher
light absorbence. The increased redness of the skin increases the
light absorption by a factor of 3. As a result, the efficacy of the
aforementioned light system is similar to that of a prior art
system operating at 60 Joules/cm.sup.2, which is known to provide
adequate results in wrinkle removal procedures. At energy density
levels as high as 20 J/cm.sup.2, it is preferable to chill the
epidermis in order to avoid a risk of a burn. Epidermis chilling is
accomplished by means of an aluminum plate, which is chilled by a
thermoelectric chiller. The plate is in contact with the skin and
chills the skin just before the handpiece is moved to the chilled
skin target, prior to treatment.
The invention has thereby converted an intense pulsed light device
for hair removal into an efficient photorejuvenation device as
well.
Example 20
An Nd:YAG laser operating at 1064 nm, 90 milliseconds pulse
duration, and energy density of 70 J/cm.sup.2 is suitable for prior
art hair removal having a spot size of 7 mm. By prior art hair
removal, absorption of light in the hair shaft melanin is limited,
with a contributory factor in hair removal being attributed to the
absorption of light by blood in the hair follicle bulb zone. Since
the energy density level of 70 J/cm.sup.2 is risky to the epidermis
of dark skin, it would be preferable to operate the laser at 40
J/cm.sup.2.
A vacuum chamber is preferably integrally formed with a handpiece
through which intense pulsed light is directed, at a distance of 1
mm from the skin target. A vacuum is applied to the skin target for
2 seconds. The blood concentration near the follicle bulb and in
the bulge at a depth of 4 and 2 mm, respectively, is increased by a
factor of 2. As a result the laser is operated with the same
efficacy at energy levels closer to 40 J/cm.sup.2 and is much
safer.
Example 21
A Dye laser emitting light at a wavelength of 585 nm, with a spot
size of 5 mm and pulse duration of 1 microsecond, is used by prior
art methods for treatment of vascular lesions, such as
telangectasia, and port wine stains, at an energy density level
ranging from 10.15 J/cm.sup.2 and for the smoothing of wrinkles at
an energy density level of 3-4 J/cm.sup.2. Some disadvantages of
the prior art method are the purpura that is often produced on the
skin during vascular treatments and the very large number of
treatments (more than 10) which are necessary for the smoothening
of wrinkles.
By applying a controlled vacuum to a vacuum chamber in contact with
a skin target, having either a moderate vacuum level of
approximately 600 miilibar or a vacuum which is modulated at a
frequency of 10 Hz for 1 seconds prior to the firing of the laser,
the efficacy of the laser is enhanced. Consequently it is possible
to treat vascular lesions at 7 J/cm.sup.2 without creating a
purpura and to remove wrinkles with a much smaller number of
treatments (5).
Example 22
A prior art diode laser operated at 810 nm or a Dye laser is
suitable for treating vascular rich psoriatic skin, wherein the
treated area per pulse is approximately 1 cm.sup.2. By employing a
vacuum chamber attached to the distal end of the handpiece of
either of these lasers, blood is drawn to the lesion and treatment
efficacy is improved. The vacuum may be applied for 2 seconds prior
to firing the laser beam.
Example 23
A deep penetrating laser, such as a pulsed diode laser at 940 nm,
an Nd:YAG laser, or an intense pulsed light source operating at an
energy density of 30 J/cm.sup.2, is suitable for thermally damaging
a gland, when a vacuum chamber is attached to the distal end of the
handpiece thereof. When vacuum is applied for a few seconds, e.g.
1.10 seconds, above a gland such as a sweat gland, excessive blood
is drawn into the gland. After the pulsed laser beam is directed to
the skin, the absorption of the laser beam by the drawn blood
generates heat in the gland, which is thereby damaged. It is
therefore possible to more efficiently thermally damage glands with
a laser or intense pulsed light source when vacuum is applied to
the skin.
Example 24
By placing a vacuum chamber on a skin target in accordance with the
present invention prior to the firing of an intense pulsed light
source, the treatment energy density level for various types of
treatment is significantly reduced with respect with that
associated with prior art devices. The treatment energy density
level is defined herein as the minimum energy density level which
creates a desired change in the skin structure, such as coagulation
of a blood vessel, denaturation of a collagen bundle, destruction
of cells in a gland, destruction of cells in a hair follicle, or
any other desired effects.
The following is the treatment energy density level for various
types of treatment performed with use of the present invention and
with use of prior art devices: a) treatment of vascular lesions,
port wine stains, telangectasia, rosacea, and spider veins with
light emitted from a dye laser unit and having a wavelength of 585
nm: 5-12 J/cm.sup.2 (present invention), 10-15 J/cm.sup.2 (prior
art); b) treatment of vascular lesions, port wine stains,
telangectasia, rosacea, and spider veins with light emitted from a
diode laser unit and having a wavelength of 940 nm: 10-30
J/cm.sup.2 (present invention), 30-40 J/cm.sup.2 (prior art); c)
treatment of vascular lesions with light emitted from an intense
pulsed non-coherent light unit and having a wavelength of 570-900
nm: 5-20 J/cm.sup.2 (present invention), 12-30 J/cm.sup.2 (prior
art); d) treatment of vascular lesions with light emitted from a
KPP laser unit manufactured by Laserscope, USA, and having a
wavelength of 532 nm: 4-8 J/cm.sup.2 (present invention), 8.16
J/cm.sup.2 (prior art); e) photorejuvination with light emitted
from a dye laser unit and having a wavelength of 585 nm: 2-4
J/cm.sup.2 and requiring 6 treatments (present invention), 2-4
J/cm.sup.2 and requiring 12 treatments (prior art); f)
photorejuvination with light emitted from a an intense pulsed
non-coherent light unit and having a wavelength ranging from
570.900 nm: 5.20 J/cm.sup.2 (present invention), approximately 30
J/cm.sup.2 (prior art); g) photorejuvination with a combined effect
of light emitted from an intense pulsed non-coherent light unit and
having a wavelength ranging from 570-900 nm and of a RF source: 10
J/cm.sup.2 for both the intense pulsed non-coherent light unit and
RF source (present invention), 20 J/cm.sup.2 for both the intense
pulsed non-coherent light unit and RF source (prior art); and h)
hair removal with light emitted from a Nd:YAG laser unit and having
a wavelength of 1604 nm: 25-35 J/cm.sup.2 (present invention),
50-70 J/cm.sup.2 (prior art).
While some embodiments of the invention have been described by way
of illustration, it will be apparent that the invention can be
carried into practice with many modifications, variations and
adaptations, and with the use of numerous equivalents or
alternative solutions that are within the scope of persons skilled
in the art, without departing from the spirit of the invention or
exceeding the scope of the claims.
* * * * *